Why We Get Fat (Lecture Notes)

This post is a summary of Gary Taubes’s lecture, “Why We Get Fat”.

Observation

The common explanation to obesity epidemic is that these populations practice sedentary lifestyle and consume excessive calories. However, it does not explain obesity epidemic in certain populations. These populations work in intensive labour condition and are malnourished, yet some of them are still obese. The theory simply describes the process of calorie accumulation, but does not describe how and why it leads to obesity. 

Hypothesis

  • Obesity is a disorder of excess fat accumulation (not energy balance, not over-eating, not sedentary behaviour)
  • Overeating and inactivity are compensatory effects, they are not causes.
  • We don’t’ get fat because we overeat, we overeat because our fat tissues are accumulating excess fat. 

Further question – What regulates excess fat accumulation?

  • Insulin, insulin is the principal regulator of fat metabolism (Yalow and Berson, 1965).
  • Release of fatty acids from fat cells requires only the negative stimulus of insulin deficiency.
  • When insulin is secreted or chronically elevated, fat accumulates in the fat tissue.
  • When insulin level drop, fat escapes from the fat tissue and the fat depots shrink.
  • We secrete insulin primarily in response to the carbohydrates in our diet.

Carbohydrate is driving insulin is driving fat.

Cahill, 2005

Conclusion

1. Obesity is a disorder of fat accumulation, not energy balance.
2. Fat accumulation is regulated fundamentally by insulin and dietary carbohydrates.
3. The only non-pharmaceutical remedy is to restrict or remove the causative agent – the carbohydrates.