Nutrition Archive

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Q. I have heard that exercising on an empty stomach burns more fat and at a faster rate. Is this true?

A. When the body is in a fasting state, several backup mechanisms ensure your muscles and brain get the necessary sugar for fuel. During exercise, after your body's sugar stores are exhausted, the body then taps into stored fat and turns that into sugar or turns protein from muscle into sugar. This has led to the hypothesis that exercising when the body is already "sugar starved" will lead to more rapid fat burning.

Can curbing your usual daily calorie intake by 10% improve health and longevity?

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There is a saying: "The less you eat, the longer you live." The rising rates of obesity have shown that Americans consume more than necessary, and cutting back on calories may be a smart move.

"People naturally gain about a pound a year, on average, beginning in middle age, so healthy weight needs to be a goal for older men," says Vasanti Malik, a research scientist in the Department of Nutrition at Harvard's T.H. Chan School of Public Health. "That is why being mindful of how many calories you really need — and perhaps cutting back some, an approach called calorie restriction — may help some men stay healthy and maybe even live longer."

Research we're watching

Gluten, a storage protein in wheat, rye, and barley, triggers inflammation and intestinal damage in people with celiac disease. Due to concern that gluten may also increase the risk of obesity, diabetes, and cardiovascular disease among healthy people, the number of people without celiac disease who have adopted a gluten-free diet grew more than threefold from 2009 to 2014.

A team led by researchers from Harvard T.H. Chan School of Public Health used 20 to 30 years of data from the 64,714 women in the Nurses' Health Study and the 45,305 men in the Health Professionals Follow-up Study to examine the relationship of dietary gluten to the risk of chronic conditions such as coronary artery disease in people without celiac disease or heart disease. All the participants had completed questionnaires on their diet and health every four years from 1986 through 2010.

New phrases showing up on packaging don't always tell you if the food is better for your health.

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You're not alone if you don't know the meaning of certain terms on food labels lately. A new language has developed to describe healthy ways to produce meat, vegetables, fruit, and other products in the grocery store. "It's not just the terms that are confusing, but also various associated health claims," says Vasanti Malik, a nutrition researcher at the Harvard T.H. Chan School of Public Health.

Organic vs. natural

Some food is labeled "organic" or "natural." What's the difference? The FDA doesn't have a definition for "natural," although it doesn't object to the term if a food does not contain added color, artificial flavors, or synthetic substances.

Some aspects of diet may diminish or heighten the effect of prescription drugs or cause harmful side effects.

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You take your pills on time each day and get your prescriptions refilled before they run out. But all that hard work to stick to your medication plan can be scuttled if your diet is undermining the drugs' effects. "I see a lot of people who don't believe in the importance of following dietary recommendations for medications. That's a concern," says Dr. Randall Zusman, a cardiologist and Harvard Medical School associate professor.

Dietary risks

The following foods, drinks, or ingredients can interfere with specific drugs.

Do a little research, follow a few rules, and make polite requests.

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Going out for dinner can be a nice way to unwind with family or friends. But if you're watching your salt intake, restaurants aren't always so relaxing. Much of their fare is loaded with sodium, a main component of salt. In fact, some entrees at popular chains contain far more than 2,300 milligrams (mg) of sodium — the recommended limit for an entire day's worth of food (see "Super-salty entree examples").

Limiting sodium is especially important for people with high blood pressure, because excess salt worsens this common condition, leaving you more prone to heart attack and stroke. If you eat out only once a month, you probably needn't worry too much. But Americans tend to eat out far more frequently — about five times a week, on average. So it's worth learning some strategies for staying within your salt budget when you eat away from home.

Research we're watching

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If you're craving a crunchy snack, a handful of cashews is a heart-healthy choice, a small study suggests.

Although they're a popular pick in nut mixes, cashews have a bit of a bad rap. Because cashews contain about 20% saturated fat, the FDA omitted them from the qualified health claim suggesting that nuts may lower heart disease risk when eaten as part of a diet low in saturated fats and cholesterol.

In the journals

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Omega-3 fish oil supplements can help prevent death from heart disease in patients who've had a heart attack, but a science advisory published March 28, 2017, in Circulation found there is no research to support their use to prevent heart disease in the general population.

Researchers reviewed all randomized clinical trials that evaluated the potential role for fish oil supplements to prevent cardiovascular disease, including two studies published before 2002 and 13 published since then. The studies assessed the clinical impact of fish oil treatment on cardiovascular outcomes, such as heart attacks, strokes, and atrial fibrillation (a heart rhythm disorder).