In the article that appeared here two weeks ago, you learned that in his book that’s now spent 19 weeks on The New York Times Bestseller list, Dr. Peter Attia stresses something in it that’s been stressed in this column repeatedly. That being proactive rather than reactive is better for your health.

Elsewhere in Outlive: The Science and Art of Longevity (Harmony, 2023), an “actionable operating manual for the practice of longevity,” Attia asserts something else that’s been written here many times. That health writers can best help you be more proactive about your health not by telling you what to do, but by serving as your “translator” when new research emerges.

With that said, let’s see if we can make sense of the “fructose survival hypothesis” as presented in a paper published in the May 2023 issue of Philosophical Transactions B - and for good reason. The paper’s authors propose that ingesting and metabolizing the “excessive” amount of fructose that so many Americans now do (primarily in the form of high-fructose corn sweetener used so frequently in today’s processed foods) “not only explains obesity but the epidemics of diabetes, hypertension, non-alcoholic fatty liver disease, obesity-associated cancers, vascular and Alzheimer’s dementia, and even aging.”

They contend ingesting too much fructose over-stimulates a survival switch that’s evolved in mammals over millions of years as a way to stave off starvation. That switch, when activated, causes you to hoard energy and store it as fat.

Activate it too often, and it leads to unhealthy amounts of body fat. It’s a process, though, that’s brought about by cellular actions you probably don’t want to read about: the reduction of adenosine trisphosphate and the suppression of mitochondrial oxidate phosphorylation, just to name two.

Still, it’s still a process of utmost importance. In fact, the paper maintains the fructose survival hypothesis “unites [all] current hypotheses on obesity,” so you can see why a greater understanding of it could help your health.

With that in mind, I’ll take the risk of oversimplifying the new findings and use an older and less scientific paper to show how weight gain comes so easily with fructose. It’s written by John Parrillo, titled “Fructose: The Ideal Carbohydrate Source for Gaining Fat,” and was published in the April 1996 issue of his own magazine.

The experiment Parrillo repeatedly orchestrated was to have competition-quality bodybuilders, well accustomed to weighing and measuring all they eat, replace 300 calories of a complex-carb food, like brown rice, with 300 calories of a simple-carb fruit high in fructose, like bananas, in their daily diet. After a few days, Parrillo would check their body-fat percentage with skin calipers and invariably find they had gained body fat.

Body fat that they would quickly lose once Parrillo told them to go back to eating 300 calories of brown rice daily instead of 300 calories of bananas. Science has since ascertained why this occurs for the reason Parrillo gave at that time: because complex carbs are “preferentially stored” as glycogen to provide energy for muscle cells, whereas fructose “gets directly converted to fat in the liver” and then gets stored as fat in fat cells.

Parrillo’s experimentations led to him alerting the world that all calories, especially carbohydrate calories, are not equal well before anyone involved in mainstream nutrition sent out a similar alert. As well as labeling fruit as “nature’s candy” and eliminating it from the diets he’d construct for bodybuilders interested in creating “perfect physiques.”

Now let’s backtrack a bit and also be clear. The paper proposing the fructose survival hypothesis doesn’t suggest what Parrillo tells bodybuilders: to avoid eating fruit.

But it shows something important to everyone, not just bodybuilders: a correlation between the increases globally in obesity and diabetes and a rise in sugar intake. The rise in sugar intake has occurred primarily through an increased consumption of sweetened beverages and processed foods, both of which tend to use (you guessed it) high-fructose corn syrup.

Now I’ve warned you about the evils of what’s seen as even modest amounts of added sugars, especially in the form of HFCS, for years. But don’t think the warning is mine alone.

In a Medical News Today article about the fructose survival hypothesis, Dr. Mir Ali, bariatric surgeon and medical director of Memorial Care Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, CA, tells Katharine Lang, “We advise our patients to minimize all sources of sugar, including fruits.”

Another interviewed for the article, Dr. Eamon Laird, a postdoctoral research fellow at the University of Limerick, Ireland, exonerates fruits. He says,“Most of us don’t eat enough fruits and we should be eating more for general health for fiber, vitamins and micronutrients,” but he does believe that in all likelihood “the biggest risk” with fructose occurs when it is added to other foods that are also high in fat and low in nutrients.