Bardet-Biedl Obesity: What It Implies about Obesity in the General Population

The Bardet-Biedl syndrome (BBS) is a rare genetic disorder. Its side effects include obesity. What might this weight gain imply about the fundamental nature of overweight?

KEY POINTS:

1. Bardet-Biedl appears to lead to weight gain independent of diet and lifestyle factors.


2. BBS also appears to be associated with changes to the hormonal environment of the fat tissue.


3. These observations seem to support the Lipophilia Hypothesis and challenge the Caloric Balance Hypothesis.

The Caloric Balance Hypothesis tells us that the only thing that matters is calories. So a positive caloric balance must drive BBS obesity. Somehow the children who have this disorder eat more calories or burn off fewer calories than children without the syndrome.

The Lipophilia Hypothesis tells us that action on the fat tissue itself causes fattening. Thus, any BBS weight gain would not result from behaviors like eating too much or under-exercising – it would be a physiological consequence of the disease itself.

Let's examine which hypothesis makes more sense:

1. Here's an interesting article: "Bardet-Biedl syndrome: beyond the cilium."[1]

The authors confirm that the syndrome is genetic and that its side effects include obesity.

2. This article is from Endocrinology: "Mini review: human obesity – lessons from monogenic disorders."[2]

The authors declare that "genetic influences on the determination of human fat mass are profound and powerful."

3. "Energy metabolism in Bardet-Biedl syndrome" -- this is from the international journal of obesity from 2003.[3]

In the abstract, the authors discuss how BBS is a "hereditary disorder caused by single gene defect." They investigated "whether energy metabolism in subjects with BBS differs from matched obese controls" and concluded:

"[There is] no evidence for systematic difference in the energy metabolism in subjects with BBS relative to other obese individuals, suggesting that the genetic basis of BBS is not associated with specific abnormalities in energy metabolism."

4. And finally, we have this article: "A review of the literature Bardet-Biedl disease and report of three cases associated with metabolic syndrome and diagnosed after the age of 50."[4]

The authors say that BBS obesity is linked with other diseases that often associate with general obesity, such as "raised blood pressure, insulin resistance, and atherogenic dyslipidemia."

This suggests that whatever causes the obesity and overweight in these patients might also be causing the other diseases of civilization – just like the Lipophilia Hypothesis predicts.

References