Understanding Leptin

An overweight individual eating 2000 cal daily and not gaining weight decides to lose weight so that his knees and back do not hurt, or a physician has identified prediabetes and his patient is worried about having to take insulin. The individual initially loses a few pounds by reducing calorie intake, but as the leptin levels drop, the thyroid signals “starvation,” which slows down the burning of fat and the weight loss stops [14].

The more frequently a person has repeated the lower calorie weight loss regime resulting in weight gain, the more leptin-resistance results. Once the person reaches a plateau and cannot lose any more weight, frustration leads to food-intake increase and leptin signals those calories to be stored as fat. Leptin is the survival hormone that enables humans to live for months with very little food.

As leptin causes the cell metabolism to slow down during any weight loss effort, it is also a factor that causes weight regain in bariatric surgery patients—particularly those candidates for adjustable gastric banding. Leptin problems are the cause of diet failures and the only solution for permanent weight loss is to learn how to master leptin levels [15].

  • • Allow 10-12 hours between the last meal of the day and breaking the fast (breakfast). Finish dinner/supper at least 3 hours before bed.
  • • Never go to bed on a full stomach.
  • • Eat at least three meals a day with 4-6 hours between meals. No snacking.
  • • Consume food slowly and in small amounts.
  • • Breakfast needs to contain a high-quality protein.
  • • Minimize carbohydrate foods.

Leptin levels follow a 24-hour natural cycle with peak levels in the evening and during the first hours of sleep. The lowest level of leptin is midday (noon to 1 pm) when it begins to gradually rise again. Obese individuals have lost their leptin rhythm [16, p. 120].

When leptin works properly, a high-leptin level controls the appetite and reduces the desire to eat [17]. People with leptin resistance have higher levels of leptin at night, but the brain does not receive the signal to control eating and individuals can raid the refrigerator or snack supply within hours after eating a large meal.

Bariatric surgery candidates with leptin resistance may also have insulin-resistance issues [16, p. 122]. Eating between meals leads to changes in hormonal signals that prevent the breakdown of fat. Insulin is released in response to an increase in blood glucose from the food consumed so that extra calories can be stored as fat. The first burst of insulin usually occurs within 10 minutes of eating with a peak around 30 minutes after a meal. The liver determines immediate energy needs and stores approximately 60% as glycogen for later use [18,19, pp. 8-9].

When muscles are not used enough to burn the glycogen, insulin facilitates storage of extra calories as fat. Insulin facilitates glucose entry into the fat cells where it is converted to glycerol to produce triglycerides [19, pp. 8-9]. Thus, high-insulin levels are a major reason calories are stored as fat and why fat cannot be broken down and used for energy.

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