Our body tends to maintain energy balance (EB) i.e the balance between energy intake (EI) and energy expenditure (EE). Our body resists the intended calorie deficit after we exercise. The more we exercise, the more the body naturally tries to compensate by altering our metabolism through a series of evolutionary-based protective mechanisms designed to prevent starvation and indefinite weight loss.
The exercise-induced weight loss becomes ineffective because the acute energy deficit is counteracted by behavioral or metabolic responses. These compensatory responses are categorized into two categories: automatic and volitional.
The automatic compensatory response is typically a metabolic consequence such as reduced resting metabolic rate, and the volitional compensatory response is typically a behavioral consequence such as increased intake of snacks.
The behavioral responses have more effect than the metabolic ones, which means the energy content of an energy-dense snack would have more of a significant impact on EB than a metabolic adaptation such as a reduction in resting metabolic rate (RMR). This is based on the concept that the rate of EI (energy intake) far exceeds the rate of EE (energy expenditure).
The energy compensation response by our body goes as much as 28% due to reduced basal energy expenditure (BEE), which means that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day.
An increase in food intake could be caused by an underlying biological mechanism to resist the energy deficit or a psychologically motivated drive to reward oneself for the increase in EE. This happens majorly due to increased frequency of eating (snacking), increased meal size, selection of larger portions, and increased energy density of the food.
We also compensate for exercise-induced EE by becoming less active and decreasing our NEAT (Non-exercise activity thermogenesis) as a result of exercise-induced fatigue. This could be caused either by a physiological mechanism like substrate depletion or a psychologically driven belief that we can “afford” to rest because of the extra energy expended during the exercise session.
Exercise influences our eating behavior by modulating both the pleasure we get from eating and the drive to eat, known as the body’s hedonic response to food. In the long term, exercise hones our appetite regulatory system, making it easier to cut down on snacking and instead eat at set times of the day. In the short term, vigorous exercise stimulates brain areas associated with reward and dependence. This makes us crave high-fat, energy-dense foods, which can negate the beneficial effects of an exercise regime.