A person reduces intake by 500 kcal/day for 30 days. Using 1 kg fat ≈ 7700 kcal, the expected weight loss is (500 × 30) / 7700 = 1.95 kg. If metabolic adaptation lowers basal energy expenditure by 150 kcal/day during the diet, what is the actual expected weight loss that month and what does that difference illustrate about set point physiology? Show calculations.

• A. About 1.95 kg actual loss; adaptation has no impact and thus set point physiology is unsupported
• B. About 2.5 kg actual loss because adaptation increases thermogenesis and therefore magnifies weight loss
• C. About 0.5 kg actual loss; most weight change is water and unrelated to energy deficit calculations
• D. About 1.36 kg actual loss; the smaller loss illustrates metabolic adaptation reducing the effective deficit and supporting set point physiology

Answer: (D)