Scientific understanding is challenging the conventional wisdom about hunger — now framing it as a scourge that afflicts not only people who get too few calories, but also those who consume mostly sugar and refined starch. Under this new understanding, people eating the wrong kind of diet can suffer from both hunger and obesity.
A more scientifically accurate view of hunger and obesity couldn’t come at a better time. Obesity affects about 40% of the U.S. population, almost one in four Americans had trouble affording food in 2021, and the price of food has risen more than 11% since this time last year.
So nutrition experts rightly applauded last week’s White House Conference on Hunger, Nutrition and Health, since the discussion steered away from helping people get enough calories and instead focused on getting people enough real food. That’s also the focus behind a multi-billion dollar Joe Biden administration initiative to end hunger in America by 2030.
The idea that the kind of food matters more than the number of calories consumed started as a heretical minority view but has gradually become mainstream. The old thinking that all calories are alike and obesity was caused by lack of willpower couldn’t explain why poverty, food deserts and obesity have been concentrated in the same communities.
“That puzzled me for many years — how could it be that people who were hungry or didn't seem to have enough money to buy enough food could be more overweight or obese than people who had lots of resources,” said Walter Willett, professor of epidemiology and nutrition at the Harvard School of Public Health.
Calories measure the amount of energy available from food, but the human body can’t be fueled up the way a car can. “We have learned a lot over the years. There are multiple lines that connect poverty, food insecurity and obesity,” Willet says. “One of the most important connections is just simply poor food quality.”
If this new scientific view is correct, it means hunger has actually contributed to the dramatic rise in obesity over the last 30 years — a 70% increase in adults, and an 85% rise in children.
Scientists still disagree over exactly what constitutes the best human diet — clashing over whether people should eat a higher proportion of fat or carbohydrates. But emerging from the fray is some agreement about the kind of diet that’s harmful to human health. Unfortunately, it includes the food that’s cheapest, most convenient, most available in poor areas, and most heavily marketed — foods and drinks that are high in sugar or corn syrup, and starchy foods such as white bread, chips and fries.
David Ludwig, an endocrinologist at Harvard School of Public Health and Boston Children’s Hospital, is lead author of a new paper that explains how hunger and obesity might be directly connected. It’s all based on the hormone insulin.
The paper, published in the European Journal of Clinical Nutrition, and including Willett as a co-author, details the way different forms of carbohydrates act in the body. When in the form of fruits, vegetables, beans or some whole grains, they are absorbed slowly because of the fibrous plant material surrounding the carbohydrates, but in white bread or sugary cereal or soda they’re absorbed fast and generate spikes of insulin. That insulin causes people to feel hungrier and put on weight.
It makes sense, Ludwig told me, if you think of this process as analogous to a teenager getting hormonal signals that spur growth. Those hormones trigger teens to eat voraciously and to use the excess calories for growth. Something similar happens in pregnancy when hormones trigger a woman to feel hungrier; the extra energy goes into growth of the fetus and placenta.
“We argued the same thing is true for obesity — that when fat cells in the body get triggered to take in too many calories, there are too few calories for the rest of the body, and that's why we get hungry,” Ludwig said. “That's surprising for people, but it's well demonstrated.”
If that idea is right, it calls for a very different solution to America’s hunger and obesity problems than the conventional view that people gain weight because they lack self-control and eat too much.
It wouldn’t be the first time our understanding of obesity got a major overhaul. Older conventional wisdom also held that dietary fat was the cause of obesity and that people should steer toward a higher carbohydrate diet. That view may have actually made people sicker and heavier.
“How long do you stick with a paradigm that's based ultimately on eat less and move more, in one form or another, when it's not working?” Ludwig asked.
It’s time to retire the old trope that for most of human evolution our species struggled for every calorie and caused us to be wired to be constantly hungry. In that narrative, only those with the most willpower and self-discipline stay thin. The narrative seems obvious the same way it must have seemed obvious for a long time that the Earth was the center of the universe.
It’s much more likely that prehistoric people ate the right kinds of food — what humans are well-adapted to eat to be strong, healthy and energetic. That includes meat, fish, dairy, fruit, vegetables and, after farming was invented, whole grains such as brown rice and wheat berries.
There can be a lot of variety in a healthy diet: Ludwig points out that traditional cultures from the Inuit to Laplanders to Plains Indians ate diets high in animal fat during much of the year, while other cultures thrive on mostly plants. What nobody seems to thrive on is sugar, white flour, soda and fries. In his experience, people choose the wrong foods for economic reasons. “Many low-income families would love to have access to healthier whole foods.”
Humans are diverse in our shapes and sizes — we don’t all have to be skinny to be healthy, and some obese people may be suffering from hunger. Can a government initiative really end hunger by 2030 — just eight years from now? The Biden administration might need more help from Congress for such an ambitious goal, but any effort that starts with a science-based approach will help save and improve many lives.
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ABOUT THE WRITER
Faye Flam is a Bloomberg Opinion columnist covering science. She is host of the “Follow the Science” podcast.
This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.
