Last year a time magazine article argued that exercise is ineffective for weight loss. This contention flew in the face of conventional wisdom, which holds that, while exercise alone may not be sufficient reach and maintain the ideal body weight, it is necessary. The article’s argument is also false. According to a new review by British and Australian researchers publish in Current Opinion in Clinical Nutrition and Metabolic Care, exercise works for some people and does not work for others as a means to lose weight. Genetic factors regulating the effect of exercise on appetite and eating behavior appear to be the main determinant in this regard. The review also reaffirms what even the Time article conceded: that exercise is indispensable to weight maintenance after weight loss.

Researchers at Creighton University Medical Center are reporting new evidence that calcium supplementation helps prevent weight gain, at least in certain populations. The new study, published in the journal Nutrition & Metabolism, looked at the effects of daily calcium supplementation, with and without vitamin D, on 870 postmenopausal women. Over the course of the supplementation period, women receiving calcium supplementation gained significantly less trunk fat than women taking a placebo. The authors of this study believe that calcium supplementation may reduce appetite, or rather, that inadequate calcium intake may spur appetite because the brain can detect low calcium levels and may stimulate a drive to eat to compensate for it.

According to a study newly published in the online Journal of the International Society of Sports Nutrition, many of the popular weight-loss diets fail to provide enough vitamins and minerals to sustain optimal health. Holistic nutritionist Jayson Calton analyzed daily menus suggested by four diets: Atkins for Life, South Beach, DASH, and Best Life–for their vitamin and mineral composition. He found that all four diets failed to provide the minimum RDI of all 27 nutrients analyzed. Calton calculated that, on average, the diets would have to have provided roughly twice the 1,745 calories they did provide to supply adequate amounts of most of the essential vitamins and minerals. According to Calton, this means that persons who follow any one of these diets could see their health compromised even as they lose weight. Ironically, the nutrient deficiency of these popular diets could also make them less effective for weight loss, as there is some evidence that vitamin and mineral malnutrition encourages overeating.

Brian Wansink of Cornell University has made a career of proving that humans cannot resist the temptation of food and that therefore the best way to avoid overeating is to avoid temptation. For example, he did that famous study showing that people ate a lot more soup without thinking they did when fed from secretly self-refilling soup bowls. Now Wansink’s at it again with a new study whose results suggest that people eat more when they place serving dishes on the same table they eat from. In the study, Wansink had subjects eat the same foods in two different circumstances. In one circumstance they served themselves from dishes that sat in front of them on a table and then ate at that table. In a second circumstance they served themselves at a counter and then took their plates to a table where they ate without the temptation of additional food in front of them. In both circumstances the subjects were instructed to eat as much or as little as they liked. Guess what? Women ate 20 percent less and men 29 percent less when they served themselves at a counter and ate at a table without serving dishes on it. That’s a handy little tip for you!

A new study by researchers at the University of Alabama-Birmingham suggests that eating a high-fat breakfast may be healthier than eating a high-carb breakfast. The study involved mice, so we’ll have to wait and see if the results translate to humans, but the findings are certainly intriguing. Mice were fed either a high-carb or a high-fat breakfast upon waking in the morning and then given different types of meals later in the day. Their metabolic profiles (blood lipid levels, body fat levels, etc.) were monitored over a period of weeks. The researchers found that the metabolic profile stayed normal when mice were fed a high-fat breakfast, whereas mice fed a high-carb breakfast gained more body fat, became more glucose intolerant and developed other features associated with metabolic syndrome. The reason appears to be that the content of the first meal of the day programs the body’s metabolism for the rest of the day. So eating a high-fat meal in the morning caused the mice to burn more fat throughout the day. This study was published in the International Journal of Obesity.

Gram for gram, calorie for calorie, high fructose corn syrup, the most commonly used sweetener in processed foods today, is more fattening than table sugar. At least for rats. This is according to a new study conducted by researchers at Princeton University and published in Pharmacology, Biochemistry and Behavior. Rats were given either water sweetened with table sugar or water sweetened with high fructose corn syrup (HFCS) at half the concentration, along with their normal diet. After several weeks, rats in the HFCS group were found to have gained significantly more fat, most of it abdominal fat, than the rats in the table sugar group. This was the case even when rats in the HFCS group did not consume more calories than their counterparts in the table sugar group. This finding suggests that the difference lies in how HFCS is metabolized within the body, not in its effect on appetite.

We eat junk food mainly because it is delicious, but our best intentions to avoid it are not helped by the fact that most of it is cheap. The results of a new study published in the Archives of Internal Medicine suggest that we would in fact eat less junk food if it cost more. Researchers compared changes in body weight and the prices of different types of foods in a pool of more than 5,000 men and women and found that, as the price of junk foods such as soda and pizza increased, body weights tended to decrease. Based on these findings, the authors of the study than an 18 percent tax on such foods would result in a decrease of 56 calories consumed per person per day and a loss of 5 pounds of body weight per person per year.

There is evidence that the effectiveness of exercise as a weight-loss method is limited by its effect on the appetite. A new study from the Obesity Research Group looked deeper into the so-called “compensation effect” by investigating the effect of exercise-induced weight loss on appetite-related peptides and the motivation to eat. Twenty-two overweight and sedentary adults engaged in a 12-week supervised exercise program consisting of five sessions of aerobic exercise per week. The subjects were asked not to alter their food intake during the study period.

The subjects lost a significant amount of weight. At the end of the study, they had higher levels of the “hunger hormone” ghrelin and higher levels of self-rated hunger in the fasted state. However, the researchers also found that exercise-induced weight loss had a stronger effect on suppressing ghrelin release and increasing the release of glucagon-like peptide-1, a satiety hormone, after meals. These latter results suggest that exercise-induced weight loss might make meals more satisfying. The authors of the study, which was published in the Journal of Clinical Endocronology and Metabolism, concluded, “Exercise-induced weight loss is associated with physiological and biopsychological changes toward an increased drive to eat in the fasting state. However, this seems to be balanced by an improved satiety response to a meal and improved sensitivity of the appetite control system.”

Everyone knows that successful runners are always light and lean, but a new study by researchers at the University of Zaragosa, Spain, suggests that body fat percentage is as important to running performance as any physiological factor. The Spanish scientists used skinfold measurements to estimate body fat percentage in 12 elite male and 12 elite female Ethiopian distance runners and compared these estimates to their race performances. They found an 80 percent correlation between skinfold measurements and race times in the men and a 78 percent correspondence in the women. All of these runners were very lean, but the leanest among them were the fastest. Body fat estimates were comparable to other physiological measurements such as forced expiratory volume in predicting performance. The study was published in the Journal of Sports Medicine and Physical Fitness.

This may be my favorite new study of the last several months. Italian researchers have proven that if you eat when you’re hungry, and only when you are hungry, you will lose weight if you are overweight and sustain your weight if you are not overweight. It sounds absurdly simple, and on one level it is, but it is a simple idea that has been obscured by certain complexities.

The core concept is that eating behaviors are regulated by both physiological sensations linked to specific underlying physiological events such as declining blood glucose levels and by conditioning, such as the conventions of eating breakfast, lunch and dinner at certain times of day. “Initial hunger” is a term that refers to the purely physiological triggers of eating. The authors of this new study hypothesized that initial hunger is the body’s true guide to how much food it needs. They further proposed that overweight individuals who were trained to recognize and respond to initial hunger–eating only when they were truly hungry instead of always at planned meal times, when food happened to be available, etc–would lose weight.

And guess what? In five months, the subjects trained to eat only when hungry for this study lost more than 10 pounds, on average–far more than members of a control group who were encourage to lose weight by means of general eating restraint (which is known to be ineffective because it is unsustainable). The study was published in Nutrition & Metabolism.