The 3 key strategies for effectively, and safely, "cutting weight"; Research based strategies for acute weight management pre-competition weigh-in

Many sports use "weight tiers / divisions" to reduce the chance of an unfair advantage. As is the case with most things, we, as humans, push these classifications right to the edge. Some athletes will undergo a significant, acute weight loss phase to attempt to enter into a lower weight tier/division. The thought being this may give them an advantage over others in that tier and improve their results / outcome of the event. 

To achieve such a rapid weight reduction, athletes use a variety of methods such as: reduced liquid ingestion; use of humidity blouses and plastic suits; reduced energy intake; fasting one day prior to the weigh-in; reduced carbohydrate and fat intake. Other more aggressive, and potentially dangerous methods are also used, such as prolonged sauna use, vomiting, diet pills, laxatives and diuretics. Rapid weight loss is common across combat sports as well as weightlifting sports and, in some cases, equestrian performance. It occurs in athletic groups irrespective of gender and younger athletes are now engaging in the practice. 

Whilst the merits of "cutting down" to enter a lower weight class are debatable and it is unclear as to how truly successful this strategy is, this won't be our focus in this article. In respect of this issue, there are other athlete's who would more naturally fit into these weight categories and may be hard pressed increasing their weight / competing in a category less suited for them.

We realize that, regardless of whether we say "it is, or isn't better to attempt the drop down in weight category" athlete's will likely do it anyway. So, if they're going to do it anyway, we'd rather they do it more effectively (as inadequate recovery may increase injury risk and reduce performance). We appreciate both sides of the issue and so this article is going to dive into the key strategies athlete's can employ to acutely lose body weight. As always, this will be from an evidence based perspective (and with athlete safety in mind).

Understanding the difference between a "weight cut" and a diet for fat loss

One of the fundamental things to understand surrounding an acute "weight cut" (AWC) is were the weight loss is actually coming from and distinguishing it from a diet focused at fat loss.

AWC is accomplished predominantly through; less food/waste in the gut, changes in body water and depletion of glycogen stores. A diet focused on losing fat is accomplished through; a calorie deficit (with diet composition contributing some importance to this, particularly if the goal is for greater retention of lean muscle mass).

Whilst they may be somewhat interrelated, one does not necessarily have to lose fat to lose weight. Shock! The short term, acute weight loss achieved through manipulation of body water, glycogen and food in the gut can be quite significant (with some athletes using these strategies to achieve more than 10% of total body weight loss). Surprisingly, this is also how many popular diets achieve that extreme short term weight loss which they herald as being a miracle fix. Whilst there may be some fat lost, it's likely predominantly a combination of the aforementioned factors making up the majority of that weight loss.


As this is a predominantly nutrition based site, we are now going to cover the key strategies we will use with clients (and which are backed with evidence for their implementation and relative safety).

Note that, these approaches may be counter-intuitive to optimal health. Elite sport and optimal health don't always (and probably less frequently than we'd care to think) go hand in hand. These practices should not be employed without guidance of an experienced professional and or clearance from your respective health care representative / GP.

Please, DO NOT USE THESE STRATEGIES FOR FAT LOSS. That is not the purpose for these methods.

Magnitude of an AWC which is relatively safe and won't significantly effect performance

Before we go into too much detail on the strategies which we can employ for an AWC, it's important to highlight how much weight an athlete can lose whilst not significantly effecting their performance.

An athlete's current state of health and wellness is important to factor in before we gauge how much we can achieve safely through an AWC and preserve performance. Hydration state, injury status, diet composition (which relates to the saturation of muscle glycogen stores) and the amount of time between the weight in and performance all need to be factored in. 

The research addressing this exact question is limited. Professor Reid Reale, a senior scientist at the Gatorade Sports Science institute has published a number of papers addressing the issue. His findings note that, under certain conditions, achieving 5% and up to 8% body mass (BM) losses may result in acceptably small impacts on health and performance.

He suggests, as a guide, that athletes with greater than 12 hours between weigh-in and competition (e.g., sports which conduct weigh-ins the day before competition), a fully hydrated, well-nourished athlete may lose and recover from up to 8% BM.

He recommends that, those weighing-in the morning of competition (with limited recovery time, e.g. ≤ ῀6 h), should aim for no more than 5% BM acute losses.


Aiming to achieve greater than this through an AWC may detriment performance but can also be potentially very dangerous (with the hazard level differing depending on the techniques employed). One such example would be from the world of judo, were, 3 months prior to the 1996 Olympic Games, the gold medal favourite in the 65kg category, Chung Se-Hoon, was found dead in a sauna. Typically weighting 74kg, it was reported that he was trying to lose 18lbs (8kg, more than 10% of his body mass) for a check in with his team.

It goes to show that, even at the elite level of sport, dangerous and arguably ineffective techniques for an ACW are being employed. To this day, it is reported that many boxers, MMA fighters and other combat sports and weightlifting athletes still engage in these practices! 

So, let's dive into the strategies which we propose are both safe, and effective, based on the current body of evidence. 

Manipulating our gut content during an AWC

One of the greatest contributors to BM which can be effectively lost without any real long term detriment to our health is our current gut content. 

Paralleling recommend dietary strategies for optimized health, this strategy involves the athlete moving from fibrous, complex carbohydrate, calorie efficient (high volume of food for relatively low kcals) foods to foods which are low in volume and relatively energy rich. Fibre rich foods and those with complex carbohydrates (such as wholegrains) should also be excluded / minimized).

Recalling back to what we said earlier, elite sport and optimal health don't always go hand in hand and many of the measures recommend to achieve a significant degree of weight loss during an AWC would be counter intuitive to informed dietary advice.

The reason why we recommend a reduction in fibrous foods and or foods containing complex carbohydrates is their respective digestive rate. Fibre slows down gut transition and draws in water to the intestinal space. Complex carbohydrates will also pass through the gut slower than other foods. High volume, calorie efficient foods will also contribute to an increase in weight. If we can reduce these foods we can then in turn reduce our body mass by having less food / waste present in the gut.

The use of this kind of restrictive diet in the context of an AWC has not been studied in depth. Indirect evidence suggests significant weight loss (1.5% BM) is achieved following 48 h of fiber restriction (≤ 10 g/d), which mirrors the effectiveness of laxative formula, with no further significant losses in most individuals. 

48 hours prior to weigh in seems a good recommendation to begin a fibre / complex carbohydrate restricted diet. It should be noted however that gut transit time between individuals can vary widely (10 - 96 hours) and so some athletes may require prolonged restriction.

Altering Glycogen storage levels for an AWC

Glycogen is our body's carbohydrate stores kept within skeletal muscle and also stored in the liver. Our body can metabolize glycogen to ultimately produce energy in times of demand. Individuals can alter their glycogen store levels through dietary adjustments (such as carbohydrate restriction) and glycogen demanding training.

Why is this important? Firstly, it is noted that glycogen is bound to water at a ratio of 1:2.7. So, for every gram of glycogen there would be roughly 3 grams of water. Secondly, it is estimated that the human body stores around 600g of glycogen at any one time and can be reduced, through exercise, by around 10%. Whilst exercise is the go to solution for many athletes, adding in a low carbohydrate (<50g a day) approach may have added effects. 

It has been shown that 7 d of a low carbohydrate diet (< 50 g/d), combined with training and a minor energy deficit (< 10%) can achieve around 2% BM reduction whilst maintaining strength, power and anaerobic capacity measures. 


The exact amount of BM loss through glycogen manipulation will depend on an athlete's pre-restriction glycogen storage levels, current exercise levels and, possibly, even their age and gender. A coach/athlete should consider the time between weigh in and competition/ performance before considering the use of this approach (factoring in how it may effect performance).


Manipulating body water during an AWC

The human body constitutes around 60% water and this percentage may even be greater in athletic populations given their atypical increased lean muscle mass. Given this, it is widely adopted that manipulating body water is the greatest contributor to acute weight loss for an AWC.

Body water can be manipulated in one of three primary ways (in relation to dietary strategies).

Dietary strategies;

The most obvious dietary strategy an athlete could employ is simply to restrict their fluid intake. A 24 h fluid restriction (< 300 ml) may result in 1.5 - 2% BM loss.

An extremely common strategy athlete's utilize is "water loading" whereby they intake greater volumes of fluid for several days before several days of fluid restriction or return to baseline fluid intake. This is used widely amongst combat sports, weight lifting sports, equestrian activities and even in bodybuilding in some cases (although the merit behind employing this technique for this given sport is questionable and likely not fully understood by the coach / athlete using it).

The strategy is employed to facilitate greater water loss through increased urination during the "water loading" phase which "tricks the body" into maintaining increased urination in a fluid restricted state.

This previously anecdotal finding was recently reflected in a study by Reale et al., (2018) who also investigated the effect of water loading on BM loss and performance outcomes. 

They found the intake of large volumes (100 mL. kg.d or ~ 7-8L/d) of water for 3 days prior to one day of fluid restriction (15 mL. kg.d) was associated with increased urine production, both during the days of high fluid consumption and fluid restriction.

Specifically, diuresis (increased or excessive production of urine) continued during fluid restriction, leading to greater fluid losses relative to fluid intake on the day as well as the losses recorded for a control group who had consumed 40 mL. kg.d (~ 3L/d) prior to this day.

The study found that water loading was effective in achieving greater BM loss (3%) following the 5 d intervention compared to a control group (who consumed around 3 litres of fluid a day and lost around 2.4%). Interestingly, they also found there to be no significant differences in performance outcomes between the two groups. More work needs to be done but the findings in this study may lead to more uniform application of the technique (in a relatively conservative manner compared to what may be seen amongst athletes concurrently).


Finally, reductions in sodium (salt) intake may also result in body water losses. In a sodium restricted state your kidneys will attempt to maintain osmotic pressure by increasing the excretion and retention of both electrolytes and fluids. 

BM losses of 1-2% have been reported in hypertensive subjects who switched to a low sodium (< 500 mg) diet for 5 days.

Whether or not similar losses would occur in "healthy" subjects is not currently known. Despite the lack of definitive evidence, reductions in sodium intake during weight cuts are common and have been employed for decades. Restricting sodium may or may not benefit athlete's during an AWC but increasing electrolyte intake via other means (through certain foods, supplements etc.) would not be recommend if the aim is to "shed" body water (as it may lead to increased retention).

In Summary

The body of literature surrounding this subject is relatively in it's infancy but some interesting data has been achieved in recent years. 

Weight manipulation for pre-competition weigh in is as much of an "art" as it is a "science" and coaches and athletes should work together to discuss which approaches are most feasible for them and trial them to gauge the effectiveness. Attempting an AWC strategy/strategies for the first time leading into an important event is likely to produce undesired results / experiences.

Athlete's should be educated on the potential harms of employing more extreme methods in place of those mentioned in this article and should also be educated on the value of "understanding their body" (which approaches work best for them, both physically and psychologically, and guarantee the most optimal result outcomes).

We're going to include a brief table to discuss the mentioned techniques in this article. 

We're also going to do a "Part II" whereby we discuss the interim re-hydration and fueling period between weigh in and performance (so as to optimize performance in the event / competition).

As always, thanks for reading and all the support!

If you think this article would help someone don't be afraid to share and let us know if you've use any of these techniques!






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OUTWRK is Edinburgh's leading nutritionist services company.

Providing research & experience based nutritional coaching for everyone ranging from internationally competing athletes to individuals simply looking to solve their dietary related issues.

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