If you fast too often or too long, your body thinks it's starving and slows down how fast it burns energy to save energy.
Scientific Claim
Frequent or prolonged fasting triggers adaptive thermogenesis, causing the body to reduce metabolic rate to conserve energy.
Original Statement
“Once you extend the fast beyond 36 hours, but this also ties in with fasting too frequently, the body recognizes a consistency pattern. And it starts to say, 'Oh, oh, oh, we're starving. We should conserve energy.' So what this is telling us is that a well-timed long fast speeds your metabolism up. But doing it too often, even with shorter fasts, or stacking calorie restriction on top of it on the days you're not fasting, will slow it down.”
Context Details
Domain
nutrition
Population
human
Subject
frequent or prolonged fasting
Action
triggers
Target
adaptive thermogenesis causing reduced metabolic rate
Intervention Details
Evidence from Studies
Supporting Evidence (2)
This study documented metabolic changes during prolonged fasting, including the observation that metabolic rate increases initially but then decreases with extended fasting. While the study doesn't explicitly mention 'adaptive thermogenesis' by name, it shows the physiological changes that would lead to this phenomenon, including declining blood glucose and insulin levels with increased ketone bodies, which are consistent with energy conservation mechanisms. The study's findings support the claim that prolonged fasting triggers metabolic adaptations that conserve energy.
This study examined long-term calorie restriction in humans and found changes in metabolic markers that suggest adaptive responses to reduced energy intake. While the study focuses on long-term restriction rather than intermittent fasting, it demonstrates that the body adapts to reduced caloric intake by altering metabolic processes, which supports the concept of adaptive thermogenesis as a response to prolonged energy restriction.