In relation to the food our kids eat every day of their lives, we do not like to associate such a phrase as “dirty little secret,” and yet over at Tufts School of Nutrition Science and Policy, a high official named Dariush Mozaffarian did that exact thing. As stated to journalist Dhruv Khullar, the quotation goes like this:
The dirty little secret is that no one really knows what caused the obesity epidemic. It’s the biggest change to human biology in modern history. But we still don’t have a good handle on why.
These days, any theory that embraces calories as the sole cause is likely to be rejected. But Mozaffarian offers a couple of possibilities:
Our bodies process carbs differently from fats, for instance; a calorie from corn leads your body to secrete more insulin than a calorie from cheese. Certain food additives seem to activate genes associated with weight gain, and things like weight loss and exercise can reset the body’s metabolic rate.
Dean Mozaffarian has also pointed out that with the relatively new concept of ultra-processed foods, various factions against sugary drinks, fast food, and harmful additives can join forces under one convenient banner.
A few details
If the obesity rate is falling here and there, it is likely not due to any improvement in the food or some enlightened practices, but because of the widespread use of GLP-1 drugs. Nevertheless, Americans are more overweight than their peers in other similar countries. In pursuit of knowledge, increasing numbers of researchers are looking not at what goes into the body, but what comes out. When traversing the environment of the gut, various foods leave bacterial signatures that reveal a lot.
A bug called B. theta is supposed to digest fiber, but if it doesn’t have enough fiber to work on, it will happily start digesting the mucus that forms the gut lining. Artificial sweeteners, along with a whole lot of other things, affect the microbiome. No one is quite sure of the details yet, but apparently humans have a lot fewer species of gut bugs than we used to, and this is not good.
Some experts say, maybe this is because we have changed. Others say, on an evolutionary timescale, not enough time has passed for us to have changed quite so much. So, it must be that the food itself is to blame. Foods do change our individual biology. They don’t just go in and then out in a different form. Along the way, they change our actual biology and our ability to cope with them and with other foods.
Another multifactorial field
A lot of things could be happening, and probably are. The additives that make food qualify as “highly processed” could be ruining the delicate taste receptors, which become confused and think they are encountering some nutritious substance, which turns out to actually be just fattening garbage. Feeling the lack, we struggle to make up for it by seeking (largely non-existent) nutritional value in yet more food. Dr. Chris van Tulleken describes overeating as probably “searching for that nutrition that never arrived.”
Research pioneer Kevin Hall, whose much-quoted study influenced the field tremendously, demonstrated for the first time that our metabolic health is disrupted by ultra-processed foods. He has pointed out such miscellaneous facts as, for instance, that a certain brand of vitamin water is sold as a health drink although a 20-ounce bottle of it contains almost as much sugar as a can of Coca-Cola. In regard to another point, it seems increasingly apparent that a food additive does not need to be physically addictive, but only needs to be irresistible enough to enable a behavioral addiction.
Nutritionist and molecular biologist Marion Nestle created the USA’s first academic food-studies program. She taught that during WWII, when many prospective soldiers had to be rejected because of health issues stemming from malnutrition during the Great Depression, the army became very concerned about nutrition — just as it did much more recently, when so many recruits were rejected because of obesity. That was when the Army, the National Academy of Sciences, and the National Research Council got together and published the first table of recommended amounts of various nutrients.
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Source: “Why Is the American Diet So Deadly?,” NewYorker.com, 01/06/25
Image by Mateuszg89/Pixabay
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