It’s popular to talk about certain foods that stimulate thermogenesis, or heat production, as a means to aid in weight loss – the most fashionable of which is probably coconut oil. While that’s all good and desirable, the heat generated upon eating makes a relatively small contribution when compared to all the heat generated by all the reactions in the body, including the process of keeping the gut in a state of continuous readiness to digest and assimilate the next meal.
All metabolic processes in the body generate heat. In other words, metabolism is unavoidably heat-generating. The minimum amount of heat generation is set by the resting metabolic rate,[*] which is, in turn, set by the thyroid hormone, among other ancillary factors. The heat generated from eating – directly related to the energy costs of digesting, absorbing, and converting the myriad of components of food into their appropriate storage forms – adds to the heat generated by the resting metabolic rate. As far as diet-related heat generation is concerned, of all the macronutrients, protein has the greatest effect. Carbohydrate has a lesser effect than protein, and fat has a negligible effect.