How Fast Should You Lose Weight on a Cut?

Older starvation-study data (the Ancel Keys-era research most of this field draws from) puts the maximum fat oxidation rate at roughly 30–40 calories per pound of body fat per day. So someone carrying 50 lbs of fat has a much higher ceiling for an aggressive deficit than someone carrying 15 lbs. This data comes from extreme conditions, not voluntary dieting, so treat it as a directional estimate rather than gospel — but it tracks with what's observed in practice: leaner people simply can't sustain the same size deficit that heavier people can.

The more fat you're carrying, the harder you can push the deficit early on. As you lean out and your fat stores shrink, that same deficit becomes proportionally larger relative to what your body can actually mobilize — at which point you should pull back rather than grinding through a deficit your body can no longer support efficiently.

• ~500 cal/day or less — under 1 lb/week — best for standard, sustainable cutting
• ~1,000 cal/day — ~1.5+ lb/week — best suited when you're carrying higher body fat and have more fat to draw from

Rather than reverse-engineering it from fat mass, a widely used estimate is to lose 1–1.5% of total body weight per week. Take your body weight and multiply by 0.01 (1%). A 180 lb person could reasonably target ~1.8 lbs/week. Since a pound of fat is roughly 3,500 calories, that works out to a daily deficit in the 600–900 calorie range for most people in that scenario — adjust within the 1–1.5% window based on how much fat you're carrying and how the scale is actually trending.

Match your deficit size to your starting body fat. Heavier individuals can run a larger deficit early on without much downside; leaner individuals need to be more conservative. As the cut progresses and body fat drops, scale the deficit back rather than holding it constant — your body simply has less to give the leaner you get.