by Don Heatrick

My final fight, aged 40 years… Choosing the right competitive fight weight class, and then making that weight is the fight before the fight!

I’m often asked questions like, “Is fighting at 127lbs ideal for someone who’s 5 ‘8”?”

Now, there’s obviously a lot that goes into deciding which fight weight class suits you best, including your fighting style.

But the most important consideration is your body composition… How much lean muscle you have, and how much body fat.

I’ve spoken extensively about body composition in my Fat Loss For Fighters guide, so I won’t go into that now. But here’s an important quote…

“A lower body fat percentage means less dead-weight, and more potential for speed and power.

This is true at whatever level you compete, and becomes increasingly critical as your fight career progresses…

You’ll also be in true striking distance of your real fight weight, once you factor in safe pre-weigh-in water-weight-loss strategies.”

The Mistake

Many fighters and coaches mistakenly believe that being as light as possible will give you the best advantage against your opponent.

It doesn’t.

Back in 2006 I personally fought for, and won three different amateur Muay Thai titles in one year

Cruiserweight (81-86kg), Light Heavyweight (75-81kg), and Middleweight (71-75kg).

I had to weigh-in for all of these amateur fights on the day of the fight too.

And much like Goldilocks and the three bears, Cruiserweight was too heavy, Middleweight was too light, and Light Heavyweight was just right!

By far my worst performance was at my lightest, for the Middleweight title. I scraped the win but I felt like crap.

I’d stopped weight training to lose some muscle mass, and I dehydrated myself extensively. I was weak, exhausted, and felt fragile. And I’ve found it’s the same for those I’ve coached too.

Muay Thai is a fighting competition, not the biggest weight cut competition.

The objective is to fight at your best – to show your best performance. Cutting too much weight destroys this.

In fact, cutting too much weight the wrong way, destroys lives.

When It Goes Too Far

The late Jordan Coe

Back in 2005, my interview with Jordan Coe at the Z1 WMC Super 4 Championships in Kuala Lumpur

Back in 2005 I had the pleasure of interviewing the late Jordan Coe. At the time, he was correctly advised how to properly make weight for fights, and he was excelling!

Sometime after this, he changed gyms in Thailand.

And to please his trainers, he reverted to dated methods of cutting weight in a sauna suit, and strived to compete at an ill-advised weight class.

It sadly cost him his life.

I vowed at the time I’d produce a free tool that fighters could use to…

  1. Safely determine what their ideal fight weight class should be
  2. Explain how to safely cut water weight to hit this target fight weight
  3. Explain how to safely rehydrate and restock stored carbs (glycogen) too

This guide, complete with Fight Weight Class Calculator at the end, fulfills that vow.

Seriously, Don’t Mess With It

Water is second only to oxygen when it comes to sustaining life. And although you can sustain a 40% loss of body mass due to starvation, a 9-12% loss of body mass due to fluid loss can kill you.

The amount of dehydration you can personally tolerate is individual. But in 1997, water loss levels ranging from just 6.7 to 10% of body weight contributed to heat-related deaths in 3 collegiate wrestlers.

The problem is your body core temperature increases 0.21ºC for every percent body mass lost during exercise in warm environmental conditions.

This increase in body core temperature causes significant physiological strain that fatigues the fighter, and can ultimately cause heat stroke and death.

You can see that temperature is a major contributor to fatal consequences of dehydration.

Therefore, water loss methods involving exposing a fighter to heat are inherently far more risky than those that don’t.

Using saunas, hot baths, or sauna suits add external heat to induce dehydration through sweating.

And exercising generates muscle heat to further induce dehydration through sweating.

Exercising in a sauna or while wearing a sauna suit combines external heating along with internal muscle heating, all while your core temperature increases due to the fact that you are dehydrating too!

This combination is VERY risky.

If you’re unlucky to be someone who’s body is sensitive to core temperature, you could be heading into a fatal situation at a relatively low level of percentage body weight loss through dehydration.

You (and your trainers) are needlessly playing Russian roulette. And you don’t need too

There are much safer methods of cutting weight that don’t expose you to risky additional heat.

For Smaller Fighters, Smaller Water Losses Cause Bigger Problems

It’s worth highlighting that smaller, lighter fighters suffer a higher percentage of body weight for the same weight dropped on the scales

Coaches should consider that smaller, lighter fighters suffer a higher percentage of body weight for the same weight dropped on the scales

For example, 3kg of water weight lost through dehydration for a 80kg fighter is just 3.75% of his body weight. But the same 3kg drop for a 50kg fighter is a potentially dangerous 6% of body weight lost in water.

Coaches should consider this, especially with junior fighters.

I make all these points to ensure you take this seriously. Cutting water weight must be done correctly and only to the right degree.

Is It All Worth It?

If the risks of excessive dehydrating are so dangerous, and failing to sufficiently rehydrate before the fight sabotages performance significantly (at least by 10%), why do it at all?

Being naturally heavier than your opponent affords you a considerable strength and power advantage

Which is why Muay Thai (and combat sports in general) have weight classes, to keep things even… and safer.

Depending on the organisation, the rules will state when matched fighters must weigh-in to demonstrate they’re evenly matched.

The time between the weigh-in and the fight determines which strategies a fighter can successfully employ to safely manipulate body weight (through water loss).

This is where fighters trade on their ability to do this without harming their performance in competition… often failing to see the potentially hazardous consequence to their immediate health in the meantime.

Fighters that have mastered the process of safely cutting water weight for the weigh-in, and then rehydrating back to approximately full weight and athletic performance, have a considerable advantage.

Studies looking at wrestling competition produce conflicting data comparing the amount of body mass recovered after weigh-in and the success in competition. The studies either showed no advantage (Horswill et al. 1994), or that winners reduced their body mass on average by 24% more than the amount that losers reduced theirs (Alderman et al. 2004).

Winning in combat sports involves many different factors beside weight-cutting, including skill level, athletic ability, conditioning, strategy, tactics, and various psychological factors (confidence, stress, determination, etc.).

However, I’d hazard a guess that studies showing no advantage from larger weight-cuts compared fighters using poorly designed weight-cutting and rehydration strategies, that left wrestlers fatigued in competition.

There is an advantage to be had from weight cutting… If it’s done well.

How To Cut Weight To Maximise Fight Performance

You’ll recall I first mentioned body composition. This is your primary objective and represents a long-term change to your body weight.

Body Fat Percentage Matters

First, achieve a body fat level that sets you in good stead for the level that you’re fighting at.

At the elite level, males must be between 5-10% body fat, and females 13-17%.

This must be done by undereating at a rate of between 500 to 1000 calories each day, with sufficient protein intake and resistance training to ensure you lose body fat and NOT muscle mass.

Losing muscle mass will not only kill your strength, power, speed, and endurance, but also reduces your “body armour”, increasing your general risk of injury both inside and outside of training and competition.

Maintaining muscle mass maintains your metabolism too, helping prevent piling fat back on again between fights.

When undereating between 500 to 1000 calories each day you can typically expect to lose body fat at a rate of between 0.5–1kg (1–2lbs) per week.

I’ve gone into depth on how you can achieve this in my Fat Loss For Fighter Guide.

But with respect to fight weight, a key take away point is…

Set yourself up for success by first achieving a competitive body fat level for the level of competition you are in.

Begin by estimating your body fat percentage by comparing a “selfie” to the following visual body fat percentage chart.

Visual representation of various body fat percentages

Visual representation of various body fat percentages

Then, decide if you are intentionally cutting fat between now and your fight date or not.

If you are, decide if you’re cutting at a moderate rate of 0.5kg (1lb) of fat per week, or an aggressive rate of 1kg (2lbs) of fat per week.

Bare in mind that under eating to burn body fat also means your training and recovery will suffer…

Targeting a moderate fat loss (of about 0.5kg or 1lb per week) is my recommendation.

Entering your start date, start weight, and fight weigh-in date into the calculator will allow you to determine what your projected weigh-in “fight” weight will be.

This projected weight includes fat loss at the (moderate or aggressive) rate you’ve selected, without losing any of your muscle mass – and therefore not losing any strength, power, speed, or endurance either.

The tool also estimates what your projected fight date body fat percentage will be too.

If you’re not looking to cut body fat, you can focus purely on training to enhance your performance. That’s a massive plus, and where elite fighters should be.

Temporary Water Weight Cutting

As well as the long-term gradual change to your body weight afforded through fat loss, fighters also exploit short-term, rapid, temporary weight loss, by manipulating their water weight.

To borrow another quote from my Fat Loss For Fighters Guide…

Half a litre of water weighs about 0.5kg (1lb). So if you sweat off a litre during training, you’re a kilo (2lbs) lighter. This isn’t fat loss.

If you drink a glass of water, that’s an instant 0.25kg (0.55lbs) added on the scales — you’ve effectively become the container for that water. This isn’t fat (or muscle) gained.

Water weight loss is the fighter’s strategy for rapid, temporary weight loss in the final week before a fight. But this shouldn’t play any part in your general training goals.

You can safely achieve temporary water weight loss in three ways…

  1. Minimal/significant dehydration
  2. Glycogen (stored carbohydrate) depletion
  3. Reducing gut volume

And your weight-cutting strategy will employ these three differently, depending on how long you have between your weigh-in and your fight, and how much you weigh to begin with…

The Fight Weight Class Calculator takes these details into account and determines all this for you.

How To Safely Use Dehydration

You become dehydrated when you lose more water (through normal body functions such as toilet visits, sweating, or moisture in your breath) than you’re taking in.

Training or fighting while even mildly dehydrated (just 1-2% of body weight) significantly impacts your performance.

It impairs your ability for both physical exertion and cognitive performance, while increasing the physiological strain (heart rate and core body temperature) associated with a given intensity of exercise.

A fighter arriving for a training session or a fight will have an increased heart rate of about 6-10bpm during exercise if they are dehydrated by 2-3% of body weight. Your body is already stressed and working harder, before you even begin to exert yourself.

And generally, you won’t feel thirsty until you’re already dehydrated by about 2% of body weight.

If you rely on self-selecting how much you drink when rehydrating after your weigh-in, drinking until you’re no longer thirsty, you’ll tend to replace fluid until you are -2% of body weight.

Thirst is not an adequate guide for a fighter’s rehydration.

It’s crucial that any dehydration you deliberately suffer to make weight is completely reversed by the time you fight. Or you’ll be a shadow of your usual self.

Although there are some final week preparations to consider, the effect of manipulating your water weight is only present for the day of the weigh-in.

Therefore, in my opinion using sauna suits in training more than a day or two before the fight is not useful… Any water a fighter may sweat off will be replaced as soon as they eat or drink again.

For me, using sauna suits to cut weight at all is a bad idea. Let me explain some other methods you can use instead…

Overnight Dehydration

Depending on how many hours you have between your weigh-in and your fight…

Simply drinking less for a day or two before your weigh-in could possibly achieve all the water loss you need.

You’ll typically dehydrate approximately 1-2% of your body weight overnight through sweating and moisture in your breath, depending on how hot and humid your bedroom is.

Also, an adult bladder can hold up to about 500ml or 0.5kg (1lb) of fluid. So your morning toilet habits can also be factored in. All of this can be used as part of your fight cut strategy…

But first you must measure it.

Weeks before the fight, for three consecutive days, weigh yourself each night before bed and again on waking (after a toilet trip, but before drinking or eating breakfast) and record the difference. 

You can use this average overnight weight loss trend to predict what you’ll need to weigh when you go to bed the night before the fight to wake up on weight.

Also, bear in mind that if you’re warmer at night you’ll sweat more. You can exploit this if the night before the fight you’re a little heavy, by wearing extra clothing to bed to amp up your overnight water loss. Just make sure you’re not so hot that your sleep is affected.

Fighters can typically dehydrate between 2.5% to 3% of body weight using this method.

Further from the fight, I’d advise you practise a trial run using this method – to find what kind of percentage weight-drop is you typically experience overnight.

The fight weight class calculation tool will advise you if this simple, convenient method is appropriate given the amount of time you have between the weigh-in and the fight.

Water Loading

If you have sufficient time between your weigh-in and your fight to dehydrate between 2.5% to 4% of your body weight and restore it again, then the safest way to achieve this is using a water loading method.

Water loading involves drinking higher than normal amounts of water for several days followed by water restriction – resulting in peeing more than you drink!

Water loading involves drinking higher than normal amounts of water for several days followed by water restriction. This naturally increases the amount that you pee, and results in you peeing more than you drink when you cut down your water intake.

This rapidly dehydrates you at the last moment, without unduly stressing your body with heat or needless exercise. Which minimises fatigue and presents you in the optimum condition to perform your best.

There are many methods you can use to water load, and the regimen I recommend is designed to not only cut water weight for the weigh-in, but also to keep you well hydrated for all your training sessions in the final week leading up to the fight too.

And to keep it simple, I don’t use salt loading either. Instead, reduce salt intake as much as possible… Avoid processed foods, fast foods, or generally adding salt to anything in the final week.

Increasing your rate of urination depends on drinking more than you’re currently accustomed to drinking…

Therefore, I advise scaling your water intake based on your general daily drinking amounts, rather than adhering to a standardised daily water intake quota.water loading program schedule

The Fight Weight Class Calculator provides you with a personal water loading plan based on your current daily drinking quantity

Overhydrating – Hyponatremia

Water loading is a significantly safer method of dehydration, as it doesn’t involve raising the body core temperature through either exercise activity or hot, humid ambient environments. 

However, it’s not without risk. Over consuming water can result in a potentially fatal condition called hyponatremia.

Drinking at a rate faster than your kidneys can deal with can lead to hyponatraemic, hypo-osmolar water intoxication with cerebral oedema.

While potentially serious, it’s rare, and can easily be avoided by only drinking at a rate of up to 800 millilitres per hour.

I’ve personally experienced hyponatremia after downing over a litre of water before a weigh-in…. I was too light for the match up, and didn’t want to give a psychological advantage to my opponent!

I ended up with a pounding headache and felt hungover. Luckily, all was ok again before the fight – but it wasn’t something I’d considered being a problem back then. Now I know much better!

Hyponatremia is also something to consider not only when water loading, but also when rehydrating after your weigh-in. More on optimal rehydrating a little later.


Don’t use diuretics! It could ultimately damage your kidneys, and it’s uncontrollable dehydration…

When you can easily control and predict your water loss using water loading. There’s no need whatsoever to risk messing things up by using diuretics.

How To Optimally Use Glycogen Depletion

Muscle isn’t only important for metabolically burning calories to fast track your fat loss…

Having more muscle also allows you to cut the more water weight safely, by running down (and then restocking) stored carbohydrate (gylcogen) in the muscle tissue itself.

Every gram of stored glycogen in your muscles has at least 3 grams of water stored with it.

By exercising those specific muscles and not re-feeding them with sufficient carbs, you’ll deplete the stored glycogen and water.

Done well, this can amount to about 4% of your body weight.

But a word of warning. If you don’t load your glycogen stores back up again before you fight, you’ll have no energy.

Without locally stored carbs in the muscles, you’ll lose strength and power, fatigue goes through the roof, and everything feels like a huge effort.

Do not fight in this state! I’ve seen many fighters live to regret a decision to cut carbs when they were unable to replenish glycogen levels again before the fight started.

Depending on how much you weigh and how lean you are…

There’s a predictable amount of glycogen/water weight you can get back on every hour after the weigh-in – if you eat and drink correctly.

The Fight Weight Class Calculator advises if you have enough time between your weigh-in and your fight to use this method without messing yourself up.

It also calculates the amount of weight you can cut from depleting glycogen stores, and advises how to fill your stores back up again at the quickest rate too.

Note, that fighters following a keto diet cannot take advantage of glycogen depletion to cut to their fight weight… They’re effectively doing this all the time, and have already lost that water weight. 

Depleting Glycogen Stores

To run down your glycogen stores and lose the associated water weight, you simply need to cut down your carb intake during the final week before the fight.

Because there’s still some intense training going on in the final week, I like to systematically scale down carb intake rather than cutting it completely.

That way, we avoid a complete energy crash and failing to adequately complete your final training sessions due to fatigue.

Beginning 7 days out from the fight, reduce your carb intake by half. The next day, half it again! Repeat this until 2-days before the fight, and on the day of the weigh-in don’t have any carbs until after the weigh-in.

Throughout this week, both protein and fat intake should remain at your typical daily amount, without dropping.

Carb cutting program schedule

The amount of time it takes to restock your glycogen stores depends on how much you weigh. Heavy fighters will take longer.

Only use carb cutting if you have time to successfully restock your glycogen stores before the fight – the Fight Weight Class Calculator will tell you!

How To Reduce Gut Content

Different foods result in drawing different amounts of water into your intestinal space. High fibre foods increase stool bulk and increase your body weight!

Adopting a low residue/fibre diet to reduce gut content in the final week before your fight will make a significant difference. In just five days you can expect to see a 1-2% body weight loss by helping to empty the bowel.

I see this extra weight loss as a “safety net” to ensure fighters can make the calculated projected weight cut for the weigh-in.

A low-residue diet is more than just eating less fibre, it also restricts foods that increase bowel activity, and make the stools looser!

The following table gives examples of foods that should or shouldn’t feature in a low-residue diet.

Low residue low fibre foods

And note that most of the foods in this table are carbohydrate foods. If you have time to successfully use glycogen depletion too… The quantities of these foods will also need reducing systematically over the week, to model the carb cutting schedule.


Some fighters use laxatives. Don’t!

It’s uncontrollable dehydration, and you could easily end up literally crapping yourself during the fight. No joke, I’ve seen this happen!

How To Rapidly Return To Full Weight & Performance

It’s one thing to get down to your fight weight, but without successfully rehydrating and restoring glycogen (carb) stores you’re destined for a miserable time and a very poor fight performance.

Both of these aspects, rehydration and restoring glycogen stores, need specific strategies.

You’ll either need to employ both, or just rehydration, depending if there is sufficient time between the weigh-in and the fight for glycogen depletion or not.

Generally, fights with a weigh-in on the same day only provide sufficient time to use dehydration, and fights with the weigh-in the day before allow glycogen depletion as well.

However, it depends not only on the time you have between weigh-in and the fight, but also how big you are.

How To Rehydrate Rapidly

Rehydration is your primary objective as soon as you’ve made weight… You need to replace the fluids you’ve lost as quickly as possible.

Drinking plain water isn’t the quickest way to do this, because it will sit in your stomach and empty very slowly.

To maximise “gastric emptying” it’s crucial to mix just the right amount of carbohydrate in solution with the water. Mixing either too much, or too little carbs slows down the rate fluid is taken into your body.

And higher concentrations of carbs can make you feel bloated and nauseous too. I personally feel sick if the carb levels are even as high as 10%.

Research also shows that you can’t just drink the same amount of fluid that you lost to rehydrate yourself. Because drinking fluids will result in urine losses.

To account for fluids wasted as you pee it out, you must drink 1.5 times the amount of fluid that you lost.

Adding sodium (salt) to a rehydration drink also helps you retain fluid rather than wasting it down the toilet.

The rate at which you drink also affects how quickly your stomach empties the fluid into your body.

Frequently drinking a moderate amount of fluid every 15 to 20 mins is ideal, and prevents overhydration (hyponatremia) too.

Optimal rehydration drink after weigh in

The ideal rehydration drink contains carbohydrate and salt to empty quickly from the gut, and reduce urine losses

The ideal rehydration drink contains 2% carbohydrate with about 1.7g of table salt per litre, and is drunk at the rate of 200ml every 20 mins.

Example Rehydration Drinks…

  • 1 cup (240ml or 8 oz) of orange juice emptied into an empty 1-litre (35 oz) bottle, then fill the rest up with water. Add to that 4 pinches of salt.
  • 355ml (12 oz) of Gatorade emptied into an empty 1-litre (35 oz) bottle, then fill the rest up with water. Add to that a pinch of salt.

The Fight Weight Class Calculator tool will tell you exactly how much fluid you must replace after your weigh-in to be fully hydrated. 

Are IV Drips Better Than Drinking For Rehydration?

There's no benefit to using an IV to rehydrate

Even Saenchai won’t gain an advantage rehydrating with a IV rather than drinking fluids

It’s not uncommon to see fighters in Thailand using intravenous (IV) drips to rehydrate after a weigh-in.

However, research shows that when you have longer than 1-hour to rehydrate, using an IV doesn’t give any advantage over oral hydration.

And an IV has some negatives to consider too.

Firstly, you’re dependent on competent medical assistance to ensure everything is done correctly. And there’s the ever present risk of picking up an infection (especially in Thailand)!

I personally don’t like handing control of something as important as this to someone else when I can handle it myself perfectly well.

Secondly, research shows that drinking your fluids, rather than pumping it into your bloodstream via a needle, makes subsequent strenuous exercise feel less strenuous.

The importance of the psychological rate of perceived effort (RPE) is not to be underestimated. And if you’re not a fan of needles, this further undermines an ideal mindset going into the fight.

We all know how important your psychological state is to your best fight performance. There’s no need to self-sabotage, and there’s no need to use IV drips to rehydrate after your weigh-in.

How To Rapidly Restore (Glycogen) Carb Stores

If you have long enough to successfully run down some, or all of your stored carbs to further boost temporary weight loss, then you need a solid strategy to get back to full fuel levels ASAP.

Get this wrong and you’ll run out of energy during the fight in a catastrophic way!

Your rehydration drinks will already contribute some of the carbs that you must restore.

In fact, it’s important to focus on these drinks first.

Don’t begin eating any food until you’ve begun to pee clear again

Your stomach won’t digest food at all well until you are sufficiently well hydrated again.

 Once you wee has stopped looking like apple juice and looks more like water, then you can start to eat something.

The amount of carbohydrate you’ll need to consume before the fight will depend on how much you’ve run down your glycogen stores and how big you are.

Research shows that the optimal rate of carbohydrate supplementation to restore glycogen levels is 0.6g of carbohydrate per kg of body weight every 30 minutes.

The Fight Weight Class Calculator tool will tell you how much you need to eat on top of the carbs you’re already getting from your rehydration drink quota.

What To Eat After The Weigh-In

To consume your carbs at the right rate, frequently eat small, easily digestible meals containing proteins, fats, and most importantly quality carbohydrates.

And only eat foods that you trust.

Before the fight is not the time to experiment with an unfamiliar food that could risk upsetting your stomach when your body hyperstimulated and more sensitive than normal.

It’s best to avoid vegetables on fight day, as high fibre foods could make you feel bloated. Stick to easily digestible, low fibre carbs like those in the low-residue table . Rice and honey are good choices.

Lunch, or your last big meal is best kept 6 hours before the fight, and should contain proteins, carbs, and fats.

3-4 hours before the fight should be a lighter meal containing protein and carbs – for example a protein shake and a banana.

Up until 1-2 hours from the fight, snacks should also be small protein and carb meals. After this, stick with drinks if needed.

How to Use The Fight Weight Class Calculator

Now you understand the how and why of making weight for your fight, now let’s use the Fight Weight Class Calculator to determine exactly what is personally appropriate for you given your unique constraints…

Essentially, all you need to do is fill in the details in the dark grey boxes at the top of the tool, and then follow the instructions given to you below that…

But let me run you through it all – to give you more detail on just what the Fight Weight Class Calculator tool is presenting to you.

Entering Your Details

1. Set your gender as male or female  – this allows the tool to advise if the body fat levels you aspire to reach are healthy or not.

2. Enter today’s date – then I can calculate how much fat loss you can cut before the fight if you need to.
You’ll need to enter using the correct format – mm/dd/yyyy – as given in the example.

3. Enter your start weight today too.
You’ll need to enter this in kg, but the amount in lbs is displayed to the right for you too.

4. Enter your approximate body fat percentage by either referring to the visual body fat percentage chart , or numbers you have from skin-fold calliper or bioelectric impedance scales tests etc.

5. Enter your weigh-in date
Again, you’ll need to enter using the correct format – mm/dd/yyyy – as given in the example when you click on it.

6. Enter your estimated weigh-in time (be pessimistic, assume it’ll be later than expected or risk getting caught out)
The time comes from a drop-down list – make sure you pick the correct am or pm time!

7. Enter your fight date
As before, you’ll need to enter using the correct format – mm/dd/yyyy – as given in the example when you click on it.

8. Enter your estimated fight time according to the fight schedule (again, be pessimistic assuming you’ll be a bit earlier than expected)
Again, the time comes from a drop-down list – make sure you pick the correct am or pm time!

9. Enter the amount of fluid you’re typically drinking each day – so the water loading schedule can be calculated for you.
You’ll need to enter this in litres, but the approximate amount of glasses is displayed to the right for you too.

10. If required, enter your intended rate of fat loss between now and the fight – I recommend a “moderate” loss to be realistic. Select “none” if you don’t need to worry about dropping fat levels.

Fat Loss & Body Fat Percentage Section

Depending on your selected rate of fat loss, this section advises of a) your required daily calorie undereat, and b) the amount of theoretical fat loss in the time available too.

Refer to my Fat Loss For Fighters Guide if you need more information on managing this correctly.

You’re also given what c) your expected body fat percentage will be assuming you’ve not lost any muscle mass.

If your predicted body fat percentage falls below at healthy level for your gender, then this will be flagged up here!

You must adjust your intended fat loss so that you don’t target an unhealthy or unachievable body fat percentage. Return to step 10 above, and select “none”. You’re lean enough!!

Walk Around Weight & Predicted Fight Weight Sections

The next section calculates your expected “walk around” weight 1 week out from the fight, before any water cutting.

This is also your full performance weight, and what we strive to re-establish before you climb into the ring to compete.

Factoring in all the variables you’ve provided, the next section calculates your best fight weight

One that you’ll successfully reach using the following recommendations, and that will result in your best fight performance.

This “fight weight” section is the most important information that you and your coach should consider before accepting to fight on the dates you’ve given.

Rehydration & Glycogen Replenishment Section

In this section you’ll be notified if you should or shouldn’t use carb cutting/glycogen depletion as part of your strategy to make weight.

You’ll also be given the total amount of fluid needed to rehydrate before the fight allowing for any loses from urination.

If carb cutting is a practical option for you, you’ll also be notified how many days of carb cutting you’ll need to hit your fight weight.

General Recommendations Section

Here you’ll find a summary of all the main details and recommendations for rehydration.

If carb cutting is practical for you, further details are also provided here regarding the amount of carbs you’ll need to consume in addition to the carbs in your rehydration drinks, and the rate these carbs are best eaten.

Water Loading & Carb Cutting Schedule

This section will display a water loading schedule if it’s necessary to make weight.

And the carb cutting details are only displayed if this is needed too – based on your personal details and the dates and times you’ve provided. Otherwise this section will remain blank.

Note that the first day on the carb cutting schedule (at -8 days) is at your regular, full carb intake level. There are in reality a maximum of 7 days of cutting carbs at a reduced intake level.

It’s possible the time you have after the weigh-in doesn’t allow for a full 7-days of cutting carbs (because you won’t fully restore your glycogen stores in time).

If this is the case, as in the following example requiring a 6-day carb cut, then you only carry out the last 6-days of the carb cutting schedule…

But note, you still carry out the full 8-days of the water loading – as you do have enough time to fully rehydrate.

Immediately below the Water Loading & Carb Cutting Schedule table, you’ll also find the recommended constant daily protein and fat quantities that should be consumed every day (within plus or minus 5g), while matching the descending daily carb quantities (within plus or minus 5g).

Reference Information Section

In the final section you’ll find the summary reference information used in calculations.

Printing The Report

To print your personalised report, click on the “Print Your Results” link below the calculator form.

A print preview will be displayed, and you can choose to either physically print, or save to a PDF instead.

Fight Weight Class Calculator

First a disclaimer…

I’ve designed this tool to set you a safe fight weight, along with an effective weight cutting and weight restoring protocol. However, just as with fighting, weight cutting comes with some risks.

You should always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you’ve read on this website.

Also, regarding GDPR and your personal data… nothing you’ve entered is saved anywhere, you’re working on a live embedded form that only you can see in your browser.

And I’ve purposely not included any name or contact fields, so you know everything is
completely anonymous and I’m not trying to steal your data!

If your browser won’t display the following calculator tool, then your country is likely blocking display…

But there is a way around this!

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Closing Notes & Next Steps

Making weight for a fight involves a mixture of long-term fat loss, and short-term temporary, rapid weight loss coming from the body’s water mass.

The methods you have to reduce this water mass are dehydration, glycogen depletion (to cut stored carbs and associated water), and reduced bulk in the gut.

Any fighter will benefit from eating a low-residue diet for at least five days leading up to a fight, to reduce gut content and the weight that goes with it.

The time you have between your weigh-in and your fight will dictate which additional methods you can safely and effectively employ to cut further water weight without risking either your health or your fight performance.

Dehydrating to lose water beyond 4% of body weight is too risky to be considered – it can lead to long-term health issues or even prove fatal.

Water loading is the safest and most controllable way to dehydrate, without contributing to the elevating core temperature that naturally occurs as you dehydrate too.

Water loading also stresses and fatigues the body least and produces the best fight performance.

Carb cutting must be done at a rate that allows you to train productively in your final week before the fight, yet leaves your glycogen stores sufficiently depleted to hit your most competitive fight weight.

You must only run your glycogen stores down to a level from which you can fully restore them again before the fight, or your fight performance will be severely compromised.

Following a systematic regimen to rehydrate and restore glycogen levels after your weigh-in is crucial if you are to fight at your best.

Achieving a fight weight and failing to regain your pre-water cut body weight is counter productive to your best fight performance.

Remember it’s a Muay Thai competition, not a weight cutting one!

Further Resources

If you want to cut body fat without losing lean muscle mass, break the cycle of ballooning up between fights, and look leaner and perform better, then check out my Fat Loss For Fighters guide here.

To learn more about the effect that carbohydrates have on your Muay Thai training and performance, you can check out my video podcast: Discussing Keto For Fighters here.

If you want to dig into developing the best fight style for you, as the unique individual that you are, take a look at my most popular video: Muay Thai Fighting Styles and Becoming a Complete Fighter here.

Once you’re ready to jump ahead into building greater fight-specific movement patterns and strength, power, speed, and endurance – check out the Muay Thai S&C Accelerator here.

Thanks for reading. I wish you greatest health and the best fight performance possible for your next fight.

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Every so often, an opportunity emerges that can redefine how we train, fight, and thrive.

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Doors Remain Open For…


If you purchased either the S&C Accelerator or Minimum Equipment Program (or both) in the past, here’s the deal:

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Seize your golden chance to level up your Muay Thai journey. Remember, the doors to Heavy Hitters Barebones will shut on midnight 31st May and won’t swing open again until November 2024…

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Don Heatrick

Founder of Heatrick Strength and Conditioning

Don Heatrick is a family man from the UK, former mechanical design engineer, European Muay Thai silver medallist, former pro Thai boxer (ranked 4th in UK while aged 40-years), a Muay Thai coach, podcast host, and the go-to expert on Muay Thai performance training with over 25 years of coaching experience.

Don helps ambitious fighters and coaches take their game to the next level by bridging the gap between Strength & Conditioning, Performance Science, and Muay Thai.

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