Diet & Weight Loss Archive

You may be storing unhealthy amounts of visceral fat even if your weight appears normal.

For decades, the body mass index (BMI) has been the gold standard for gauging obesity-related heart disease risk. But this handy tool doesn't always tell the whole story. It extrapolates your body fat percentage based on your height and weight (see www.health.harvard.edu/bmi-calculator). But the formula can't assess how or where your body stores its excess fat — a distinction that is crucial for cardiovascular health. By some estimates, the BMI misclassifies nearly 50% of people who are at higher disease risk from excess fat, meaning that you can be overfat even when you're not overweight.

The secret life of belly fat

Some people are genetically programmed to have a lot of fat tissue under the skin, which is deployed to store extra food energy during times of scarcity. But other people have very few of these designated fat cells, explains Dr. Christos Mantzoros, professor of medicine at Harvard-affiliated Beth Israel Deaconess Medical Center.

Research we're watching

People who carry excess weight but have normal blood pressure, blood sugar, and cholesterol values are sometimes dubbed "fat but fit." But they're still more likely to develop heart disease than people who aren't overweight, a new study suggests.

Researchers analyzed more than 7,600 cases of heart disease that occurred over a 12-year period in 10 European countries. They also used data from 10,000 healthy people without heart disease as a comparison group. Compared with people at a healthy weight, those who were overweight or obese had up to a 28% higher risk of developing heart disease.

Research we're watching

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Close to a third of Americans say they use artificial sweeteners on a daily basis. Popular examples include aspartame (Equal, Nutra­Sweet), sucralose (Splenda), and stevia (Truvia, Pure Via). They're all available in packets and are also added to soda, yogurt, and other foods.

But do these sugar substitutes actually help you lose weight? New research suggests they do not. In fact, these zero-calorie additives may have the opposite effect — and possibly even increase the risk of high blood pressure, diabetes, and heart disease.

News briefs

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If you haven't been good about eating a healthy diet, take heart: A Harvard study published July 13, 2017, in The New England Journal of Medicine found that changing to one of three scientifically developed healthy eating programs was associated with longer life. The healthy diets included the Alternate Healthy Eating Index, the Alternate Mediterranean Diet, and the Dietary Approaches to Stop Hypertension (DASH) diet. Scientists looked at self-reported diet and health data from nearly 74,000 healthy men and women who significantly improved their diets and maintained them for 12 years. Scientists then looked at participants' risk of death for another 12 years. The results: people who improved their diet the most were up to 17% less likely to die, whereas those whose diets worsened the most were up to 14% more likely to die. This study strongly indicates that improving your diet, even if you start in middle age, can add years to your life — and vice versa. If you're re-evaluating your diet, check out the Harvard Special Health Report Healthy Eating for a Healthy Heart (www.health.harvard.edu/HEHH).

Research we're watching

Not only is obesity a risk factor for flu complications, but it might actually make the flu vaccine less effective, says a study published online June 6, 2017, by the International Journal of Obesity. Scientists at the University of North Carolina at Chapel Hill found that the flu shot provides less protection in people who are obese.

The study compared flu rates in 1,022 people during two recent flu seasons. All participants were vaccinated against the flu. The researchers looked at immune response to the vaccine and also tracked who went on to get the virus. They found that nearly 10% of obese participants got the flu, compared with 5% of their healthy-weight counterparts. This is bad news, because individuals with a body mass index of 40 or higher are also more prone to flu complications.

The type and amount of fat, carbohydrate, sugar, and salt in our food supply has changed over the years — for better and for worse.

Remember when packaged foods emblazoned with the words "fat free" seemed to be everywhere? Then came labels boasting "zero grams of trans fat." "Sugar free" and "low sodium" claims soon joined the chorus. These days, gluten-free foods are all the rage.

For the most part, these food industry trends echoed the nutritional mantras of the time and were designed to improve our health — especially cardiovascular health. Not only is heart disease the nation's leading killer, there's overwhelming evidence that better dietary choices could prevent many heart attacks and strokes. But just how successful have these efforts been?

A Netflix original movie about a young woman’s struggle with anorexia nervosa is raising questions among parents about whether the movie might glamorize the disorder, and how best to talk to children about this topic.

News briefs

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Unless you have celiac disease, banning gluten from your diet won't boost your heart health—and may actually hurt it, suggests an observational study published May 2, 2017, in The BMJ. Gluten is a protein in wheat, barley, and rye. In people with celiac disease, eating gluten triggers the body to attack the small intestine, causing inflammation and leading to malnutrition and gastrointestinal distress. The inflammation, in turn, can increase heart disease risk. In these people, eliminating gluten stops the attack on the small intestine, reduces inflammation, and helps reduce heart disease risk.

A Harvard research team wondered whether people without celiac disease might also lower their heart disease risk by eliminating gluten from their diets. In a study of more than 110,000 healthy men and women followed for about 25 years, the researchers did not find a clear difference in the number of heart attacks that occurred among people who ate the most gluten each day, compared with people who ate the least. However, in people who avoided gluten by avoiding whole grains — which contain valuable nutrients — the risk of heart disease rose. So, if you're among the great majority of people who don't have celiac disease, avoiding gluten won't reduce your risk of heart disease, and it might increase the risk if it means you cut back on whole grains.

Research we're watching

While obesity presents a number of health risks for older adults, weight loss is often accompanied by a reduction in muscle tissue and loss of strength. A team led by researchers at Baylor College of Medicine set out to determine whether more exercise or specific types of exercise would help preserve muscle during weight loss.

The researchers randomly assigned 103 obese women and 57 obese men over age 65 to one of four groups. Three groups participated in a reduced-calorie diet plus one of three exercise programs — aerobic training, resistance training, or combined aerobic and resistance training — while the fourth, a control group, only received information on healthful eating.

Stomach balloons and other devices may help people eat (or absorb) less food. But does the weight loss last?

For the millions of Americans who have obesity, the burden of excess weight is much more than meets the eye. This chronic, debilitating condition leaves people prone to many serious illnesses, including heart disease. But for many, diet and exercise often prove frustratingly futile (see "What's a healthy weight?")