Scott Alexander examines different theories of weight gain, focusing on the roles of metabolism and appetite/exercise drive, and concludes that individual metabolic differences likely play a significant role in weight management. Longer summary

Scott Alexander explores four positions on the thermodynamics of weight gain, focusing on the debate between position 2 (weight gain depends on calories but metabolism varies) and position 3 (weight gain depends on calories but appetite/exercise drive varies). He dismisses positions 1 and 4 as unrealistic. Scott provides evidence for metabolic differences between individuals, including genetic studies and twin experiments. He also discusses the possibility of metabolism changing over time, drawing from personal experience. While acknowledging the lack of strong evidence for drastic metabolic changes, Scott concludes that people who struggle with weight loss due to their metabolism may have a valid point. Shorter summary