Interaction of variables in statistical analysis

Interaction of Variables

Overeating: Interaction of variables

As obesity rates climb, there has been a proliferation of research to determine what weight loss methods are effective and ineffective. However, human beings do not live in laboratories, and multiple factors can affect their eating and exercise behaviors. Of course, some studies attempt to meticulously track how many calories subjects consume and how much activity subjects engage in over a specific period of time. But these studies are invariably of short duration, and cumbersome to administer. The result is that experimental and observational data on what promotes weight loss is often contradictory and frustrating for dieters. Overeating is caused by an interaction of multiple variables, including total calories consumed, perceptions of certain foods, and emotional 'triggers' for overeating that are not always immediately apparent.

Conventional wisdom, even amongst scientists, has been it is not what subjects eat but the amount of calories that they eat that are significant in terms of weight loss. However, some studies indicate that overeating is caused by specific types of food consumption, specifically carbohydrates. According to the pioneering Duke University Medical Center, a leading research center in the treatment of obesity, in a study of dieters randomly assigned to high-protein, low-carbohydrate diet plans vs. those assigned to standard low-calorie plans, the low-carb dieters lost "26 pounds...lost more body fat, and lowered their triglyceride levels and raised their HDL, or good cholesterol, more than the low-fat dieters," who lost an average of only 14 pounds and did not show as significant an improvement in lowering their triglycerides and raising their HDL (Study: Low-carb diet more effective than low-fat diet, 2004, Duke Medicine News and Communications).

However, in a recent Journal of the American Medical Association study in which "25 young, healthy men and women were deliberately fed nearly 1,000 excess calories a day for 56 days, but with diets that varied in the amounts of protein and fat," it was found that all gained weight and in fact the low-protein dieters gained the least weight, although they did lose the most lean body mass (Winslow 2012). Regardless, the findings of this study suggested that high-protein diets are no panacea for weight loss. However, although the low-carb diet group in the Duke University study was instructed to only count carbohydrates, rather than calories, low-carbohydrate foods like meat tends to be much more satiating than other types of foods. Psychologically, the subjects likely felt less deprived than the low-calorie group whose portions were restricted and who ate foods that tended to be much less satiating and higher in carbohydrates. Because the high-protein group was allowed foods like steak and bacon, they may have felt less like they were 'on a diet' than the other group, which also improved their psychological attitude towards the diet.