A caloric deficit occurs when you eat fewer calories than your Total Daily Energy Expenditure (TDEE). This forces your body to use stored energy (fat) for fuel, resulting in weight loss.
How Much Deficit?
- Small deficit (250–500 cal/day): 0.5–1 lb/week loss. Sustainable, preserves muscle.
- Moderate deficit (500–750 cal/day): 1–1.5 lb/week. Effective but requires tracking.
- Aggressive deficit (1000+ cal/day): 2+ lb/week. Risk of muscle loss and metabolic slowdown.
Key Principle
One pound of body fat ≈ 3,500 calories. A 500 cal/day deficit ≈ 1 lb/week loss. Combine with adequate protein (0.8–1g/lb bodyweight) and strength training to preserve muscle during a deficit.
Diet Breaks and Refeed Days
Some approaches build in periodic days or weeks at maintenance calories to help manage hunger hormones (leptin, ghrelin) and psychological fatigue during long cutting phases. Research on their metabolic benefit is mixed, but many people find they improve diet adherence over the long run, which matters more than any small physiological edge.
Why the Scale Isn't the Whole Story
Water retention, glycogen stores, and digestive contents can shift daily scale weight by several pounds independent of actual fat loss. Tracking a 7-day rolling average, rather than day-to-day fluctuations, gives a much more reliable picture of whether a caloric deficit is working.