What a Weight Cut Does to Mood and Performance

Scope: weight-class sports only. This covers rapid weight loss to make a scale number at a weigh-in. The evidence comes from judo, and the same logic applies to powerlifting, weightlifting, boxing, MMA and wrestling. Peaking for a physique or bodybuilding stage is a different, nearly opposite process and is covered separately.

Overview

Athletes cut weight so they can compete at close to full strength against lighter opponents. A systematic review of judo research asks what a rapid cut actually costs. Its answer has two parts. Mood worsens reliably. Measured strength and power mostly hold up, with mixed results across studies.

The evidence base

Lakicevic and colleagues systematically reviewed 14 studies covering 1,103 judo athletes. Each study involved a loss of 5% or more of body mass within 7 days. They grouped the findings into physiological and performance measures, blood markers, and psychological well-being.^[1]

Mood: the most consistent effect

Psychological measures gave the clearest signal in the review. In the studies that used the Profile of Mood States questionnaire, tension, anger and fatigue rose and vigour fell in athletes who cut rapidly.^[1]