July 27, 2025

by Carmel Wroth, Health Editor

This week, scientists wanted to know: Is obesity higher in industrialized societies because we move less? Or is it something about how we eat? And, we take a hard look at high-protein snacks. Plus: The FDA is reconsidering safety warnings on hormone replacement therapy.

It’s diet — not lack of exercise — that fuels obesity, study finds

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It’s hard to believe amid today’s eye-popping obesity statistics, but the condition was almost nonexistent in the U.S. in the 1800s. Over the last century, it became increasingly common in industrialized nations, though it remains rare among people who live more traditional lifestyles, such as the Hadza hunter-gatherers of Tanzania.

One common explanation for the change, NPR’s Maria Godoy reports, is that in developed societies people have gotten less active. The assumption is that we burn fewer calories each day, leading to weight gain over time.

But a new study, turns that assumption on its head. Researchers compared the daily total calorie burn for people from 34 different countries and cultures around the world, from hunter-gatherers and farming populations, to people in sedentary jobs in Europe and the U.S.

"Actually, the total calories burned per day is really similar across these populations, even though the lifestyle and the activity levels are really different," says study author Herman Pontzer, a professor at Duke University.

And that finding offers strong evidence that diet — not a lack of physical activity — is the major driver of weight gain and obesity in our modern world.

Pontzer's past research has suggested that our bodies tend to adjust how we expend energy to keep our total calorie burn stable within a pretty narrow range.The new study adds to other recent research that suggests food is the biggest driver in obesity.

In the U.S. today, our food supply is now dominated by ultra-processed food. And the study found that populations that got more of their calories from ultra-processed foods tended to have more obesity.

Still, don't quit your gym membership! Exercise is extremely beneficial for both mental and physical health in many ways that have nothing to do with weight.

Read more about the research.

PLUS: What we know about the health risks of ultraprocessed foods

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Does hormone therapy for menopause really need a ‘black box’ safety warning?

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Hormone therapy for symptoms of menopause has seen its reputation swing in recent decades. In 2002, it fell out of favor after researchers partly halted a large study, the Women's Health Initiative, out of concerns over increased risk of cancer and stroke. Since then, researchers and doctors have determined the cancer risk was overstated, and doctors have started prescribing the drugs again.

But the label on these medications carries a black box warning, the strongest safety label the Food and Drug Association can put on a prescription medication, as NPR’s Katia Riddle reports. The label warns the therapies carry risks for endometrial and breast cancer, cardiovascular disorders and dementia.

Now that warning is getting a fresh look by the FDA which convened a recent panel to discuss it. A dozen doctors including obstetrician JoAnn Pinkerton spoke on the panel and urged the removal of the black box on low-dose estrogen treatment.

Pinkerton argues that the warning labels make women reluctant to take medications that can be beneficial for addressing symptoms associated with menopause, including frequent urinary tract infections, vaginal dryness and pain during sexual intercourse.

" The boxed warning is not supported by science," says Pinkerton. "It overstates risk."

Recent studies suggest the cancer risks of some hormone therapies are quite low and there are significant benefits for women going through menopause.

Obstetricians and gynecologists interviewed for this story agreed they would like to see the black box label removed for low-dose vaginal estrogen treatments that carry lower cancer risk.

Low-dose treatments, unlike other systemic hormone therapy treatments that are absorbed by the whole body, are delivered locally — through a cream or a ring.

They expressed reticence, however, about removing labels for systemic estrogen, which carries a different risk profile for cancer.

" For the vast majority of people, the risk is low, even for systemic hormone therapy," says Dr. Monica Christmas, an OB-GYN who regularly prescribes such treatments to her patients, "but it's not zero."

Read more about the debate over the label and the pros and cons of hormone replacement therapies.

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Are high-protein snacks worth the hype? Here's how to assess

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Seems like every other post on my Instagram is someone urging me to eat more protein. Protein stepped into the spotlight as the nutrient du jour in recent years as keto and other high-protein diets took off, Reyna Gobel reports.

Health and fitness influencers started to push everyone to eat more muscle-building foods in every meal (deep-fried cottage cheese Doritos anyone?) The nutrient is so ubiquitous online that one influencer begs protein to leave him alone for five minutes.

And it has now taken over the snack food aisles, with "high-protein" or "protein-packed" labels on the front of products as diverse as sweet rolls, chips and pretzels. There's even a high-protein version of a Snickers bar.
Of course, these claims don't always mean the food is good for you or even a good source of protein.

"You'll see chips labeled high protein," says Stefan Pasiakos, director of the Center for Human Performance Optimization at the Pennington Biomedical Research Center. "In reality, they're probably not, but people are now trying to jump all over it."

Snack-makers often market protein front and center on their packaging without mentioning the food's sugar content, says Pasiakos.

Saying something is "high protein" can be a way of working around federal regulations limiting health claims manufacturers can make, while still signaling to consumers that a food might be good for them.

So how do you determine whether a high-protein snack will really help you meet your protein goals and stick to a healthy diet? Turns out some simple calculations can go a long way.

Read on for tips for calculating if a snack has a good amount of protein compared to its sugar and calorie content.

Plus: Teens are trying to bulk up on protein supplements. What should parents watch for?

We hope you enjoyed these stories. Find more of NPR's health journalism online.

All best,
Carmel Wroth and your NPR Health editors

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