Supplemental results from the Comprehensive Assessment of the Long-term Effects of Restricting Intake of Energy (CALERIE) trial provide new insights into food cravings, specific types of foods craved, and their role in weight control.
Cravings are really normal; almost everyone has them, says corresponding author Susan Roberts, PhD, director of the USDA HNRCA's Energy Metabolism Laboratory. At the start of the study, 91 percent of the participants reported having food cravings, which are defined as an intense desire to eat a specific food. Most people feel guilty about having food cravings, says Roberts, but the results of this study indicate that they are so normal that nobody needs to feel they are unusual in this respect.
In addition, the results indicate that cravings don't go away during dieting. In fact, 94 percent of the study participants reported cravings after six months of dieting. However, Roberts says, participants who lost a greater percentage of body weight gave in to their cravings less frequently. Allowing yourself to have the foods you crave, but doing so less frequently may be one of the most important keys to successful weight control, she adds.
Roberts and colleagues observed that successful weight loss was related not only to how often people gave in to their cravings, but also to the types of foods they craved. Participants with a higher percentage of weight loss actually craved foods with higher energy (calorie) density, compared with those who lost a lower percentage of body weight, says Roberts, who is also a professor at the Friedman School of Nutrition Science and Policy at Tufts University. Energy-dense foods, such as chocolate and some salty snacks, are those that pack the most calories per unit of volume, explains Cheryl Gilhooly, PhD, MPH, research dietitian and first author of the study, as compared to less energy-dense foods like fruits and vegetables, which have fewer calories per unit of volume.
These findings suggest, says Roberts, that cravings are for calories, not carbohydrate, as is widely assumed. What is commonly called carbohydrate addiction should probably be relabeled as calorie addiction, she added. Some of the most commonly craved foods among study participants were foods that have high sugar plus fat, such as chocolate, and salty snacks, such as chips and French fries. The craved foods do have carbohydrate, but they also have fat, and some protein, too. The most identifiable thing about the foods people crave is that they are highly dense in calories, Roberts deduces.
The study, which was part of the one-year CALERIE trial, involved 32 overweight but otherwise healthy women, 20 to 42 years of age, who were randomly assigned to two diets that differed in glycemic load, a measurement of how quickly the carbohydrates in a person's diet are converted to blood sugar.
Participants completed food craving questionnaires that assessed the foods craved, the frequency and strength of cravings, and how often cravings led to eating the desired food. Researchers collected information from these questionnaires, along with data from dietary intake records and measures of weight change over time. Primary results from the CALERIE study were reported in an earlier issue of Friedman Nutrition Notes , available at nutrition.tufts/news/notes/2007-03.html. This is the first study of long-term changes in food cravings in a calorie-restriction program, Roberts says. If individuals understand that they can expect cravings and that those cravings will be for calorie-dense foods, it might help in their weight management. One thing to do is to substitute foods that taste similar but have fewer calories, since the craving can be satisfied by related tastes.
Roberts and colleagues conclude that cravings for energy-dense foods are common. Although they caution that additional long-term studies are needed to confirm their findings, they write that their results suggest that people attempting to lose weight and maintain weight loss may benefit from advice to accept that food cravings may not decrease in frequency. Controlling the frequency of giving in to cravings, rather than suppressing them, they say, may be an important area of emphasis in future weight control programs.
This work was supported by the Agricultural Research Service of the U.S. Department of Agriculture, and by grants from the National Institutes of Health and the Boston Obesity Nutrition Research Center. For more information about ongoing recruitment for the second phase of the CALERIE study at Tufts, visit hnrc.tufts/studies/2520.shtml.
Gilhooly CH, Das SK, Golden JK, McCrory MA, Dallal GE, Saltzman E, Kramer FM, Roberts SB. International Journal of Obesity ; Advance Electronic version 26 June 2007; doi: 10.1038/sj.ijo.0803672. Food cravings and energy regulation: the characteristics of craved foods and their relationship with eating behaviors and weight change during 6 months of dietary energy restriction.
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight centers, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy. For two decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations. Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies.
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