Weight Loss: Willpower or Biology?

“It’s all about eating less, exercising more.”

Obesity and overweight affect two-thirds of American adults.  You’ve probably heard this oversimplification of a plan to lose excess pounds, and from a basic science point of view, that’s what it boils down to.  Unfortunately, the real life situation is more complicated.

I’ve talked to my patients for years about something called the set-point theory:  Our body has an internal regulator for body weight, kind of like the thermostat in your house.  When your house gets too cold, the thermostat turns on the furnace to warm it back up to its set point.  Likewise, our own weight “thermostat” (in the hypothalamus of the brain) drives strong hunger signals when we lose weight, to try to bring weight back up.  Recent research backs this up, with more discoveries all the time about these hormonal signals from the hypothalamus, combined with hormones from fat tissue itself — particularly leptin.  When fat cells decrease, leptin levels fall, creating an overpowering biological drive to eat.

Is there anything we can do to fight against our own physiology?

  • When you approach weight loss, do it gradually (about 1/2 – 1 pound per week) — avoid extreme calorie restriction.
  • Be conscious about portion sizes, and plan nutritious meals and snacks ahead to avoid temptation.  If hunger kicks in, at least you’ll have healthy foods to choose.
  • Regular exercise is key:  the ideal is 1 hour of moderate exercise, 6-7 days per week.  You can also try “burst” or interval training to kick up your metabolism.
  • Get rid of the “diet” mindset, and think about lifestyle change:  adopt a long-term healthy approach to eating, including smaller portion sizes.  Plan on this to last a lifetime; don’t look forward to going back to your “normal” (unhealthy) way of eating.

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