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Want To Lose Weight?

The notion that the more you exercise, the more weight you’ll lose could disappoint you. You would be better off focusing on what you’re eating. That’s the word from a study examining daily energy expenditure of 332 adults in five countries, including the U.S. The participants wore devices that recorded their activity levels for a week, and the researchers used that information to calculate the number of calories each person burned using standard measurements. They found that moderate activity - the equivalent of walking a couple of miles per day - burned about 200 calories more than amounts expended by sedentary people, but that more strenuous activity didn’t add up to more calories burned. The findings suggest that the body adapts itself to the extra effort and burns the same calories more efficiently. "The most physically active people expended the same amount of calories each day as people who were only moderately active," explained study leader Herman Pontzer, a professor at the City University of New York.  He emphasized that exercise is good for you and can help with weight loss, but its impact isn’t as great as you may have thought.

My take? Practical experience shows us that exercise won’t always result in significant weight loss, especially for those who take in more calories as they increase physical activity. My own experience is that exercise alone is much less effective at promoting and maintaining weight loss than exercise combined with a positive change in eating habits. Diet is key.

Better Sleep Through Weight Loss

If you’re overweight, don’t sleep well and lack energy during the day, losing a few pounds might help fix all that. It worked for obese mice. Researchers at the Perelman School of Medicine at the University of Pennsylvania fed half the mice in their study regular mouse chow and the other half chow with more than three times more fat. After 8 weeks some of the mice in each group were switched to the opposite diet. Not surprisingly, those that had been on the high fat diet lost weight while those that had been eating regular mouse chow gained. After the ninth week, the mice on the high fat diet weighed 30 percent more than the other mice, slept an hour longer per day and were more likely to fall asleep during the day. However, the “diet switch” mice in both groups had completely different sleep/wake profiles, leading the researchers to conclude that changes in body weight are a key factor in regulating sleep. If you're overweight and feel tired during the day, losing only a small amount weight may result in better sleep and less daytime fatigue, the researchers reported. Will what works in mice really help humans sleep better? Stay tuned.

Vegan, Vegetarian Diets For Weight Loss

If you want to lose weight, and you’re willing to give up the traditional American way of eating, a vegan or vegetarian diet may be the way to go. Researchers from Harvard’s T.H. Chan School of Public Health conducted a meta-analysis to determine the effects of vegetarian eating on weight. They narrowed down 1,513 studies to the 12 most relevant trials comparing vegan diets or vegetarian plans (including eggs and dairy products) to the average American diet. The 12 trials included data on 1,151 individuals ranging in age from 18 to 82. Some were obese or diabetic. Analysis showed that people on vegetarian diets lost about 4.4 pounds within a year, while those on a vegan diet lost an additional 5.5 pounds during the same time frame. In the studies reviewed, the losses were compared to a control group with no changes in diet. In news reports, Frank Hu of the Harvard School of Public Health, an author of the investigation said that the meta-analysis didn’t compare the weight loss effects of vegan and vegetarian diets to a low carbohydrate, low fat or any other diet strategy, but found that they seemed to out-perform the average American diet. 

Water v. Diet Soda For Weight Loss

Replacing diet soda with plain water might help you lose more weight, especially if you’re already on a diet. Researchers at the University of Nottingham in the UK recruited 89 overweight and obese women ages 27 to 40 who usually drank diet sodas at lunch and asked half of them to switch to water. The others were instructed to continue drinking diet sodas after lunch five times a week for the 24-week duration of the study. Of the 89 women who initially enrolled, 62 completed the study. Those who switched their lunchtime drink to water lost about 8.8 kilograms (19.4 pounds), compared to 7.6 kilograms (16.8 pounds) for the women who continued to drink diet soda. Another plus: the research team reported improvements in insulin sensitivity in the women who switched to water. Even though the difference in weight loss between the two groups was small, diet drinks definitely have another downside. Earlier studies have linked them to obesity, type 2 diabetes and cardiovascular disease. 

Counting Bites For Weight Loss

Can you lose weight without counting calories? Researchers at Brigham Young University think so. Participants in a month-long study lost about four pounds each simply by counting the number of bites they took per day. The investigators recruited 61 individuals and began the investigation by asking them to count the number of bites of food and gulps of drinks they took for a day. They then asked the participants to cut those totals by 20 to 30 percent, while recording every bite and gulp. The researchers maintain that to lose weight you have to first focus on the amount you eat, and then about the kind of food you're eating - in other words, think about quantity before quality. The study participants counted their bites and their liquid intake and emailed or texted their totals to the researchers at the end of each day. Along the way, 20 of the participants dropped out because they had a hard time keeping count, but the other 41 completed the study. Next the researchers want to see if those 41 individuals manage to keep their weight off - or better yet, continue counting.

Thumbs Down On Low-Fat Diets

Low-fat diets have been losing their luster for some time, and now an analysis from Brigham and Women's Hospital in Boston and Harvard Medical School has shown that they don't lead to more weight loss than low-carb or more palatable Mediterranean diets. The researchers reviewed the results of 53 studies containing data on 68,128 adults and saw no difference between the average weight loss due to low-fat diets and higher fat diets. In fact, they concluded that reduced-fat diets led to weight loss only when compared to no diet at all, and resulted in less weight loss than low-carb plans (the review team pointed out that differences in weight change were only about 2.5 pounds). The low-fat diets included in the studies analyzed ranged from those that permitted only 10 percent or fewer calories from fat, to those allowing 30 percent or fewer fat calories. Because fat contains more than twice the calories per gram as carbohydrates and protein, the rationale for low fat diets has been that "reducing fat intake will naturally lead to weight loss," said research leader Deidre Tobias, noting that the evidence from the investigation "clearly suggests otherwise."

The Path to More Weight Loss

If you’ve been on track to lose weight by following the national recommendations to exercise 150 minutes a week, new research from Canada suggests that you can boost your results by doubling your exercise time to 300 minutes a week. This simple strategy worked for a group of postmenopausal women in a yearlong study. The investigators enrolled 384 women whose BMI ranged from 22 (a healthy weight) to 40 (obese) and divided them into two groups. Half the women were asked to exercise the recommended 150 minutes a week. The other half committed to five hours (300 minutes) of exercise per week. All the women were non-smokers, had no other medical diagnosis, and were not on hormone replacement therapy. None of them changed their diets, but all were asked to exercise intensely enough to raise their heart rate for at least half their exercise session to 65 to 75 percent of their heart rate reserve – the difference between resting heart rate and maximum heart rate – by performing aerobic activity. Most of the women worked out on an elliptical trainer, walked, biked or ran. The participants who exercised for 5 hours a week lost significantly more weight, lost more belly fat, dropped their BMI and pared their waist circumference and waist-to-hip ratio to a greater degree than did the women who exercised for only 2.5 hours a week. The exercise effects were most pronounced for the obese women, the researchers reported. And since body fat is linked to an increased risk of breast cancer, they noted that the weight loss can help lower the risk. In addition, by paying attention to diet, you could likely lose even more weight with the extra exercise. 

Morning Light and Your Weight

If you want to slim down, you might try getting up earlier in the morning. A small study from Northwestern University in Chicago suggests that the timing of your daily exposure to moderate levels of light may influence body mass index (BMI) and body fat. The researchers found that people who received more exposure to moderate or high intensity light in the morning had a lower body mass index and a lower percentage of body fat than those who got most of their exposure to light later in the day. Only 23 adults, most of them women, mean age 26, participated in the study. All were healthy. They each wore a wrist monitor for seven days to determine the patterns of their exposure to light. Study co-author Ivy N. Cheung said that the results emphasize the importance of getting most of your exposure to moderate or higher intensity light early in the day, and that the new findings lend support to earlier evidence that changes in environmental light exposure may affect body weight regulation.

Yo-Yo Dieting and Cancer

The suspicion that yo-yo dieting – repeated weight loss and regaining, also termed “weight cycling” – could be linked to cancer comes from a number of studies in both animals and humans. The results of those studies suggested that weight cycling might negatively affect key biological processes that protect and repair cells, which could lead to cancer. Now dieters concerned about this potential effect may be able to rest a bit easier. A newly published report has found no association between weight cycling and any type of cancer in men or women. A team of American Cancer Society researchers examined this issue by reviewing data from an investigation that lasted 17 years. They accumulated detailed dietary information on more than 132,000 men and women ages 50 to 74 who were participating in the Cancer Prevention Study II, which was focused on the effect of nutrition on cancer incidence and deaths. The researchers reviewed weight cycling and the incidence of cancer in general and for 15 individual cancers. Over the 17 years of the Cancer Prevention Study more than 25,000 participants did develop cancer, but based on the investigation’s findings lead researcher Victoria Stevens, Ph.D. said that the last thing people struggling to lose weight need worry about is that regaining might lead to cancer. Yo-yo dieting may not be the threat we thought it was.

Potato Extract for Weight Loss

Consuming polyphenols, a class of antioxidants found in potato extract, may hold promise as a strategy to avoid obesity. This news comes from researchers at Canada's McGill University, who studied the effects these compounds obtained from a variety of potato that is particularly rich in polyphenols. The investigators tested the extract in mice that had been fed a diet high in fat and refined carbohydrates. To begin, they put the mice on a 10-week long diet designed to fatten them up. The animals that started out weighing an average of 25 grams gained about 16 grams on the diet, but a second group of mice on the same diet with potato extract added gained only seven grams. The research team was so surprised at the results that they repeated the study to confirm the outcome. Don't think you can get similar results by upping your intake of potatoes, however. You would need to eat 30 potatoes a day (every day) to get the amount of polyphenols given the mice in the McGill study. The extract needs to be tested in humans to see if it is safe and has similar effects, and researchers will have to determine the optimal dose for men and women. If those studies pan out, the team anticipates making the extract available in supplement form or as an ingredient for cooking.