UFC Weight Cut: How Fighters Make Weight and the Risks

Contents

A UFC weight cut usually has two parts: weeks of dieting during camp, then a rapid water cut before an official weigh-in held between 9 and 11 a.m. the day before the fight. Fighters then have more than 24 hours to rehydrate. One study of MMA athletes recorded body-mass drops of around 8% in the final week, followed by an even bigger regain before the fight. This is why regulators treat extreme weight cutting as one of the sport’s main safety problems.

How UFC weigh-ins work

Official weigh-ins take place the morning before the event. Non-title fighters get a one-pound allowance, and title fighters must hit the exact limit (UFC, 2024).

Rule	What it means
Timing	The day before fight night, 9–11 a.m. local time
Non-title bouts	One-pound allowance over the division limit
Title bouts	At or under the exact championship weight
Missed weight	Forfeit a percentage of the purse to the opponent, a catchweight bout, or cancellation
Extra time	Up to one additional hour to make weight, depending on the athletic commission

Source: UFC, 2024.

Morning weigh-ins are relatively new. They were first used at UFC 199 in June 2016 under rules from the California State Athletic Commission (CSAC), which let fighters weigh in from 10 a.m. to 2 p.m. the day before. The stated goal was to reduce severe dehydration and give athletes more time to recover (UFC, 2016).

UFC division limits

Division	lb	kg
Strawweight	115	52.2
Flyweight	125	56.7
Bantamweight	135	61.2
Featherweight	145	65.8
Lightweight	155	70.3
Welterweight	170	77.1
Middleweight	185	83.9
Light heavyweight	205	93.0
Heavyweight	265	120.2

Source: UFC, 2024. Limits checked September 2026. Confirm with your event’s current rulebook. For every MMA class in kilograms, see our MMA weight classes chart.

Why do UFC fighters cut weight at all?

They cut to fight opponents who are, on paper, smaller than they are. The ACSM’s expert consensus on weight-category sports describes the logic: athletes try to gain a theoretical advantage by competing in a division below their day-to-day body mass. They get there with a mix of chronic strategies (losing body fat) and acute manipulations over hours to days before the weigh-in (Burke et al., 2021).

In MMA the incentive is especially strong. The weigh-in is the day before the fight, so a fighter has more than a day to put weight back on. If your opponent cuts and you don’t, you may face someone noticeably heavier on fight night. That arms race is how MMA cuts can become extreme, and why commissions keep stepping in.

How do UFC fighters cut weight?

Most fighters lose body fat over a camp of several weeks, then shed water, gut content and glycogen in the last few days. The final step is sweating out the remaining weight in the last 24 hours before stepping on the scale.

A typical MMA cut looks like this:

1. Camp (weeks out): a calorie deficit to bring down body fat and “walk-around” weight.
2. Fight week: manipulating fluid and sodium intake (often water loading), cutting fiber and reducing carbohydrates to lower gut content and glycogen-bound water.
3. Final 24 hours: fluid restriction plus active or passive sweating: sauna, hot baths, training in sweat suits.
4. After weigh-in: fluids, electrolytes and carbohydrates to regain as much as possible before the fight. See how to rehydrate after a weigh-in.

The last step is where the danger sits. In a study of UK MMA athletes, 43% reported using a sauna and 43% reported training in plastic suits to make weight (Matthews & Nicholas, 2017). The authors said the size of the cuts and the methods used were comparable to those that have previously caused deaths.

How much weight do UFC fighters cut?

The UFC doesn’t publish cut sizes, but the research gives a clear picture: many MMA fighters drop a large share of their body weight in the final week and regain more than that before the fight.

Finding	Number	Source
Body-mass loss in the week before weigh-in	5.6 kg (8%) on average	Matthews & Nicholas, 2017
Regain in ~32 hours between weigh-in and fight	7.4 kg (11.7%) on average	Matthews & Nicholas, 2017
Hydration at the official weigh-in	57% dehydrated, 43% severely dehydrated	Matthews & Nicholas, 2017
Fighters regaining 10%+ of body weight by fight time	41%	CSAC study, reported by ESPN, 2017

The Matthews and Nicholas study was small (seven athletes), but the regain was larger than the loss, which the authors called a novel finding. They suggested the 32-hour gap between weigh-in and fight might explain it. That is the trade-off with early weigh-ins: more time to recover also means more room to cut. This is one reason the ACSM consensus (below) lists shorter weigh-in-to-competition windows as a safer-practice measure.

To put 10% in context, ESPN gave the example of a 155-lb lightweight who weighs 170.5 lb on fight day. That fighter is effectively competing as a welterweight.

Policy changes after deaths and near-misses

Regulators have responded in two main ways. Some try to discourage cutting (California’s plan). Others make dehydration visible and disqualifying (ONE Championship’s hydration tests).

California’s 10-point plan (2017)

CSAC executive officer Andy Foster called extreme weight cutting “a clear and present danger to mixed martial arts” and compared it to the NFL’s concussion problem (ESPN, 2017). The commission passed his 10-point plan unanimously in May 2017, and it took effect on June 15 that year (Sherdog, 2017). Key elements:

• A 20% fine on win bonus and show purse for missing weight.
• New weight classes at 165, 175, 195 and 225 lb.
• A fight-day weight check to flag fighters who regain more than 10% of their body weight after weigh-in.
• Weight-class restrictions for repeat offenders.
• Weight checks 30 and 10 days out for high-profile title fights.

Promotions weren’t required to adopt the new classes, and the UFC’s divisions are unchanged: there is still a 15-lb gap between lightweight and welterweight (UFC, 2024).

ONE Championship’s hydration testing (2016–today)

In December 2015, ONE Championship flyweight Yang Jianbing was rushed to hospital with dehydration and heat stroke after a failed weight cut before ONE Championship 35. He was pronounced dead in Pasay, Philippines, on December 11 (Sherdog, 2015).

ONE announced a new system that took effect in January 2016. Athletes submit their walking and training weights, weights are checked daily during fight week, urine specific gravity is tested, and IV rehydration is banned. Today, a urine specific gravity of 1.0250 or lower passes, and anything above fails (ONE Championship, 2024).

Approach	Main tools	Source
UFC	Morning weigh-in the day before, 1-lb allowance in non-title bouts, purse forfeiture for misses	UFC, 2024
California (CSAC) plan	Fines, fight-day 10% regain check, extra weight classes	Sherdog, 2017
ONE Championship	Hydration test to make weight (urine specific gravity ≤ 1.0250), IV rehydration banned	ONE, 2024; Sherdog, 2015

The American College of Sports Medicine’s 2021 expert consensus lists three rule-level measures that support safer practice: minimum competition weights based on body composition, shorter gaps between weigh-in and competition, and bans on unhealthy weight-loss techniques (Burke et al., 2021).

A safer approach to an MMA weight cut

Choose a division you can make with a small final water cut, lose most of the weight as fat during camp, and have someone qualified supervise the last few days. The ACSM consensus also recommends individual guidance from a sports nutrition professional (Burke et al., 2021).

• Pick the right division. If you can only make it by dehydrating hard, it’s the wrong class. Our guide on how much weight you can cut helps you set a realistic target.
• Start early. The more you lose as fat over camp, the smaller your fight-week cut has to be.
• Keep the acute cut small and supervised. Never sauna or bathe alone, and stop at the first warning sign.
• Plan the rehydration before the cut. Know exactly what you’ll drink and eat, and when.
• Track the trend, not a single weigh-in. Daily morning weights show you early whether you’re on course.

Warning signs, stop immediately: dizziness, confusion, a racing or irregular heartbeat, cramps, nausea, or no longer sweating while still hot.

MyFightPrep maps your weight trend toward fight date and plans water, salt and fight week, so the final cut stays small. It’s free.

Important

This guide is general information, not medical advice. Rapid weight loss through dehydration can cause kidney injury, heat stroke and, in the worst cases, death. Work with your coach, a doctor and ideally a sports dietitian, and follow your athletic commission’s rules. If you are young or new to the sport, avoid acute water cuts altogether. If you experience any warning signs, stop and seek medical help.

Frequently asked questions

How do UFC fighters cut weight?

Most diet down over a fight camp, then shed water in the final days by manipulating fluid, sodium and carbohydrate intake and sweating before the official weigh-in, held between 9 and 11 a.m. the day before the fight. They then have more than 24 hours to rehydrate and refuel before competing.

How much weight do UFC fighters cut?

The UFC doesn't publish this. In one study of UK MMA athletes, body mass fell by about 8% in the week before weigh-in and then rose by 11.7% before the fight. A California commission study found that 41% of fighters regained 10% or more of their body weight by fight time.

What happens if a UFC fighter misses weight?

According to the UFC, a fighter who misses weight can forfeit a percentage of their purse to the opponent, the bout can be moved to a catchweight, or the fight can be canceled. Depending on the athletic commission, fighters may get up to one extra hour to make the limit.

Do UFC fighters get a weight allowance?

Yes, in non-title fights only. Fighters may weigh in one pound over the division limit, so 171 lb for a 170-lb welterweight bout. Title fights require weighing in at or under the exact limit.

Sources

This guide is based on the works below. Numbers in the text refer to them.

1. UFC (2024). Understanding UFC Weight Classes and Weigh-Ins
2. UFC (2016). New weigh-in procedure used at UFC 199
3. Okamoto B (ESPN) (2017). Ten-point plan intended to curb weight cutting coming to California
4. Critchfield T (Sherdog) (2017). CSAC Unanimously Passes Significant New Weight-Cutting Regulations
5. Sherdog (2015). One Championship Adopts New Weigh-In Policy Following Recent Fighter Death
6. ONE Championship (2024). ONE 166: Qatar Weigh-In & Hydration Test Results
7. Matthews JJ, Nicholas C (2017). Extreme Rapid Weight Loss and Rapid Weight Gain Observed in UK Mixed Martial Arts Athletes Preparing for Competition
8. Burke LM, Slater GJ, Matthews JJ, Langan-Evans C, Horswill CA (2021). ACSM Expert Consensus Statement on Weight Loss in Weight-Category Sports