Headlines Say Fructose Drives Obesity. Research Doesn’t.

It’s like some kind of holy grail. Obesity prevalence keeps rising and everyone (including ourselves) wants to know why. So headlines saying “major study claims to identify the root cause of obesity” really do grab our attention. News reports are pelting us with headlines saying fructose drives obesity. The only trouble is, the headlines are false. There’s no study at the heart of all this reporting. Just a hypothesis.

Apparently “scientists have a great hypothesis about fructose in obesity” doesn’t have enough zing.

A Hypothesis with Credibility

The fructose survival hypothesis is behind all this reporting. In a nutshell, it supposes that fructose plays a unique role as the spark for obesity because it can reset energy metabolism through ATP at a cellular level. The article that prompted these headlines is not a study that presents us with compelling new evidence to support this hypothesis. Rather, it is a solid scholarly review of evidence, authored by Richard Johnson, Laura Sánchez-Lozada, and Miguel Lanaspa. They summarize what we know and describe the need for further research.

One of the giants of obesity research, George Bray, wrote a commentary to go with this review. He says:

“I, like Johnson and his colleagues, believe that fructose plays a role in the obesity epidemic. Johnson and colleagues have identified several important functions of fructose in the human body – it tends to be lipogenic due to its different point of entry into the metabolic machinery in the liver than glucose.”

In last year’s epic meeting on theories, conjectures, and evidence about the causes of obesity, this hypothesis held up well among the many others in discussion.

It is a very credible hypothesis. It deserves attention, not distortion.

The Unsatisfying Quest for Simplicity

But all the reporting on this hypothesis is profoundly misleading because the reporters want to say, “This is it! We have the answer that explains this excess of obesity. Fructose drives the obesity epidemic.”

This is a gross distortion. Obesity is a complex disease with many factors that contribute to it. Fructose might explain a key pathway. It doesn’t explain the whole problem, just as no single factor explains cancer.

This quest for simplicity is not only unsatisfying. It perpetuates a mistaken belief that obesity is a simple problem that must have a simple solution. It’s not and it doesn’t.

Click here for the review by Johnson et al and here for the commentary by Bray. For Johnson’s further discussions of this in proceedings of the Royal Society, click here.

Decayed Steering Wheel, photograph by lost places, licensed under CC BY 2.0

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October 26, 2023