If It’s Not the Calories, What Is It?

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.

Your responses and feedback are welcome!

Source: “Why Is the American Diet So Deadly?,” NewYorker.com, 01/06/25
Image by Mateuszg89/Pixabay

Killer Diet on the Loose

In “Why is the American Diet So Deadly,” Dhruv Khullar mentions a Frenchman, Guillaume Raineri, who moved to Maryland, USA, and experienced a particularly personal form of culture shock. Every meal seemed to contain too much sugar, too much salt, and too much food, period. So he became a human lab rat, participating in an official scientific study.

This involved spending a month in an environment that could be described as monastic, or perhaps even carceral, learning firsthand that the entire secret of a successful animal study is to control as many variables as possible:

He was not allowed to go outside unsupervised, owing to the risk that he might sneak a few morsels of unsanctioned food.

Over the course of the trials, he was given both extremely nutritious, sensible meals, and, at other times, a plethora of calorie-dense, processed foods. Results were meticulously recorded, and the whole story is pretty interesting. But sadly, most Americans will never have the opportunity to understand so much about the damage we do to ourselves through incautious eating habits. Who devises these complicated research projects?

It needed to be faced

At the point in history when it started to become apparent that more Americans were overweight than ever before, sugar-sweetened beverages and saturated fat quickly became the “usual suspects.” But an investigator for the National Institutes of Health, Kevin Hall, pointed the finger directly at a third possibility: ultra-processed food, informally known as UPF. He suspected that equally as important as the “what” is the “how.” Industrial techniques and chemical modifications seemed the likely culprits.

In a study published in 2019, Hall invited twenty people to spend a month at the NIH Clinical Center, where his team measured how their bodies responded to different types of food. (Many researchers rely instead on surveys of what people recall eating.) For two weeks, participants ate a minimally processed diet, mostly consisting of “Group 1” foods such as salmon and brown rice; for the other two weeks, they ate an ultra-processed or “Group 4” diet, in which at least 80% of the calories came from the most objectional food choices.

When participants were on the ultra-processed diet, they ate 500 calories more per day and put on an average of two pounds. They ate meals faster; their bodies secreted more insulin; their blood contained more glucose. When participants were on the minimally processed diet, they lost about two pounds. Researchers observed a rise in levels of an appetite-suppressing hormone and a decline in the one that makes us feel hungry.

It was not clear why ultra-processed diets led people to eat more, or what exactly these foods did to their bodies. Still, a few factors stood out. The first was energy density, measured in calories per gram of food. Dehydration, which increases shelf life and lowers transport costs, makes many ultra-processed foods (chips, jerky, pork rinds) energy-dense.

A little surprise

The second, hyper-palatability, was a focus of one of Hall’s collaborators, Tera Fazzino. Long ago, evolution trained us to like sweet, salty, and rich foods because, on the most basic level, they help us survive. Hyper-palatable foods — those esoteric combinations of fat and sugar, or fat and salt, or salt and carbs — cater to these tastes, but are rare in nature. A grape is high in sugar but low in fat, and the typical person can stop eating after one, leading to a suspicion that maybe sugar is not so blameworthy after all. A slice of cheesecake is high in both sugar and fat, and the typical person feels compelled to devour it.

Your responses and feedback are welcome!

Source: “Why Is the American Diet So Deadly?”, The New Yorker, 01/06/25
Photo by Alexander Grey/Pexels