Why Do MMA Fighters Starve & Dehydrate Before Fights? The Weight Cut Explained

If you’ve ever tuned into a mixed martial arts weigh-in and wondered how a fighter who looks like a hulking middleweight squeezed into a lightweight division just 24 hours earlier, you’ve just scratched the surface of MMA’s most controversial tradition — weight cutting. That fighter hugging a jug of water like it’s a childhood teddy bear? They’re about to rehydrate after one of the most grueling rituals in combat sports.

Weight cutting and rehydration in MMA is a delicate, risky, and sometimes dangerous balancing act. Let’s take a closer look at this high-stakes process that has become deeply entrenched in fight culture.

Why Weight Cutting Exists in MMA

In mixed martial arts (and most combat sports), fighters are divided into weight classes to level the playing field. The catch? Many fighters want to be the biggest and strongest competitor in their class. To achieve this, athletes often undergo drastic weight cuts to hit a lower weight class before ballooning back up once the weigh-in is done.

The science is simple: The human body is made up of roughly 60% water, and water is the easiest weight to shed fast. Fighters can drop anywhere between 5 to 11 kilograms (11 to 24 pounds) of water weight in a matter of days. After stepping off the weigh-in scale, they begin the all-important rehydration process, aiming to regain most of that lost weight before fight night.

While some call this practice a “necessary evil,” critics argue it borders on dangerous and unsportsmanlike. Promotions like ONE Championship have introduced hydration tests to reduce extreme cuts, but weight cutting remains widespread across the MMA world.

How Fighters Cut Weight

1) Saunas and Sauna Suits

In the final 48 hours before weigh-ins, it’s common to find fighters dressed in layers of clothing or sweat suits inside saunas. The goal is to sweat profusely and shed water weight. Trash bags wrapped around the torso? Sadly, it’s not a fashion statement — it’s a desperate attempt to sweat every last drop.

While effective, overuse of saunas can lead to dangerous levels of dehydration, dizziness, and even blackouts.

2) Hot Baths

Epsom salt hot baths are a slightly more relaxing (but still intense) alternative to saunas. The salts help draw moisture out of the skin. Fighters often submerge themselves for several rounds of hot baths, followed by wrapping themselves in towels or blankets to continue sweating.

3) Water Loading and Restriction

One of the sneakier tactics in weight cutting is water loading. Fighters may drink up to 7-8 liters of water per day for a few days, only to dramatically reduce their intake 24 to 48 hours before weigh-ins. This tricks the body into continuing to expel water at a high rate, even when water intake has stopped.

4) Light Exercise

Low-intensity cardio, such as cycling in a sauna suit, is another method fighters use to sweat while conserving energy. This practice is less taxing than prolonged sauna sessions but still contributes to significant water loss.

The Rehydration Phase

Once weigh-ins are completed, the mission shifts to replenishing lost fluids and nutrients — but rehydration isn’t as simple as chugging water.

What Fighters Rehydrate With:

• Electrolyte-rich sports drinks to restore sodium, potassium, and magnesium levels.
• Coconut water for natural electrolytes.
• IV fluids (banned in many promotions now) were once a staple for instant rehydration.
• High-water-content foods like watermelon or oranges.
• Potassium-packed snacks like bananas or sweet potatoes to help muscle function.

Hydration is a science. Fighters need to reintroduce fluids and nutrients gradually to avoid shocking the body and experiencing bloating, nausea, or cramping.

The Health Risks of Rapid Weight Cutting

The dangers of extreme weight cuts are real and can be life-threatening:

1) Severe Dehydration

Water loss affects everything — from muscle function to blood circulation. Dehydration thickens the blood, putting pressure on the heart and kidneys. Fighters often suffer from headaches, weakness, and cognitive fog right before rehydration.

2) Electrolyte Imbalance

Electrolytes help regulate heartbeat and nerve signals. When potassium and sodium levels drop too low, it can trigger arrhythmias, muscle cramps, or even seizures.

3) Increased Risk of Concussions

Less fluid around the brain equals less cushioning. Fighters cutting too much water may be more susceptible to concussions, as their brains have reduced protection during impact.

4) Kidney and Cardiac Damage

Long-term damage to kidneys and cardiovascular health is a growing concern among veteran fighters who’ve cut weight repeatedly throughout their careers.

5) Hormonal Disruption

Rapid cycles of weight fluctuation (yo-yo dieting) can disrupt hormone levels, lowering testosterone in men and impacting metabolic function.

The Push for Safer Practices

In recent years, MMA organizations and athletic commissions have taken steps to make the sport safer:

• ONE Championship’s hydration tests prevent fighters from competing if they’re dehydrated during weigh-ins.
• Some promotions are exploring same-day weigh-ins to discourage drastic cuts.
• Others advocate for fighters to compete closer to their natural walking weight, emphasizing performance over size advantages.

Despite these efforts, the practice remains a hot topic in the sport, with calls for even stricter regulations.

The Hard Truth: Weight Cutting Doesn’t Win Fights

Here’s the kicker: dropping weight may give you a size advantage, but it won’t substitute for skill, strategy, or conditioning. Top-tier fighters focus on improving their technique and fight IQ first.

If you’re an aspiring MMA athlete, prioritize learning the craft before worrying about weight manipulation. As the saying goes, “A bigger, tired fighter will always lose to a smaller, fresher one.”

Final Thoughts

Weight cutting and rehydration remain a gritty, controversial aspect of modern MMA. While it has become part of the culture, more fighters and coaches are exploring safer approaches that prioritize long-term health over short-term gains. After all, stepping into the cage should be about showcasing skill — not testing the limits of the human body in a sauna.