Sugar Cravings: The Real Skinny

Concern among the general public and scientific communities about obesity has resulted in the development of all kinds of diet aids: low fat this, low carb that.  On the low carb side of things, we’ve seen a proliferation of sugarless sweeteners being touted as the way to satisfy your sweet tooth without packing on the pounds.

I’ve stated previously that artificial sweeteners are problematic, and can actual contribute to weight gain.

A recently published study sheds some light on why we crave sweets and may help us to understand how we can satisfy those sugar cravings and maintain a healthy weight.

The study looked at the glucose metabolism of the brains of rats who had been kept in a fasting state.  It involves an enzyme, glucokinase.  When the rats were offered pure glucose or foods high in glucose along with a regular diet, they preferred the higher glucose sources.  The longer the rats fasted, the higher their levels of glucokinase, and the more they preferred high glucose foods.  The converse was also found to be true: lower levels of glucokinase activity led to lower glucose and overall food consumption.

The study also looked at whether or not a sweet substitute, fructose, would satisfy the fasted rats in the way high glucose foods did and found that it did not.  This suggests the regulation of sugar intake by glucokinase is specific for glucose.

Some of the study’s findings are believed to hold true for humans.  Studies have shown people with mutations that lower levels of glucokinase have lower body weights; those with mutations that raise levels of glucokinase have higher body weights.

The authors’ conclude:

This mechanism may explain the observation that diets high in carbohydrate are associated with weight gain in mice (62) and why low glycemic index diets produce weight loss (41). It also provides a possible CNS mechanism to explain the often-described phenomena of the “sweet tooth” and carbohydrate craving, particularly for high glycemic index foods.

Key Points

  1. The best way to manage blood sugar and weight is with a low glycemic diet and an appropriate caloric intake.
  2. Fasting or extreme calorie restriction will increase sugar cravings in susceptible individuals.
  3. Trying to fool your brain with artificial sweeteners won’t work.

Sucralose Affects Glycemic and Hormonal Responses to an Oral Glucose Load
Glucokinase activity in the arcuate nucleus regulates glucose intake.
Familial hyperglycemia due to mutations in glucokinase.
The second activating glucokinase mutation (A456V): implications for glucose homeostasis diabetes therapy.