Nutrition
5:2 Fast Day Calorie Cap
The 5:2 fast day calorie cap sets low-day energy targets with protein priority—spread small meals and avoid stacking with accidental weekday deficits.
The 5:2 fast day calorie cap limits intake on two weekly low days—classically near five hundred to six hundred calories for smaller bodies and up to roughly eight hundred for larger active men, always individualized. Protein should stay relatively high per calorie on fast days to protect lean mass.
Spreading two small meals beats one starvation sitting.
Common questions
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Can you eat 800 calories on 5:2 fast days?
Some larger or very active people use higher caps with dietitian input—the principle is a defined low day, not zero fuel before hard training.
Related terms
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