Week of October 27, 2008
Contact: Sarah Wally, (202) 328-7744
Protein: Are You Getting What You Need?
Karen Collins, MS, RD, CDN
American Institute for Cancer Research
Trimming excess body fat is one of the top recommendations to lower risk of cancer and other chronic diseases. But new research suggests that efforts to lose extra fat may be thwarted if protein needs are not met while implementing beneficial diet and exercise programs.
One new study, recently published in the Journal of the American Dietetic Association, looked at three groups of women involved in a weight reduction program. The women, all post-menopausal and obese, were randomly assigned to one of three groups: a diet-only group that reduced calorie consumption by about 400 calories a day and two other groups that made smaller calorie cuts and participated in supervised exercise three days a week (one group at low intensity and the other at high intensity).
The good news: Women in all three groups lost weight, averaging about 24 pounds after five months. However, even in the exercising groups, about a third of the weight lost was not fat, but lean muscle tissue. Those who lost more fat than muscle? Women with a higher dietary protein intake, a constant that held true regardless of group assignment.
Earlier research, published in the Journal of Nutrition in 2005, found similar results among a population of middle-aged obese women. The study, which looked at the interaction of dietary protein and exercise on body composition during weight loss concluded the following: Women who got little exercise and ate a protein level normally considered adequate for people maintaining their weight lost the most muscle tissue; those with similar protein intake but more exercise lost less muscle; and those that performed aerobic and strength-training exercise and ate more protein lost the least muscle and the most fat.
What’s most interesting about this research is the notion that a protein level normally considered adequate may not be enough for those trying to lose weight. To that point, a 2006 analysis published in the American Journal of Clinical Nutrition concluded that people trying to lose weight might benefit from more protein than someone maintaining weight.
While the traditional approach to estimating protein needs is based on a percentage of total calorie intake, some experts suggest that an estimate based on body size (or weight) might be more appropriate. One recommendation to facilitate better lean muscle retention during weight loss is to divide someone’s current weight (expressed in pounds) in half and use that figure as an estimate for recommended grams of protein per day.
Also note that underestimation of protein needs may be more of a problem for some people than others. People who are more overweight and those with insulin resistance may need more protein than others. Some research also suggests that older adults may need a little extra protein to maintain their existing muscle tissue. However, people with kidney or liver disease should check with their physician before significantly boosting protein intake.
Increasing protein consumption does not have to mean eating more meat. In fact, sticking to a mostly plant-based diet that provides dietary fiber and a wide range of vitamins, minerals and phytochemicals is vital for good health. Fortunately many plant-based foods supply protein, including whole grains, vegetables, beans, nuts and seeds. Most adults can easily meet their protein needs with a balanced diet that includes five to six ounces a day of lean poultry, fish or meat and three servings of dairy products (or alternatives) in addition to the protein from plant based foods. Those who prefer to omit or minimize meat or dairy products need to include multiple servings of vegetarian sources of protein like beans, nuts, seeds and perhaps some eggs.
Our Mission: The American Institute for Cancer Research champions the latest and most authoritative scientific research from around the world on cancer prevention and survival through diet, weight and physical activity, so that we can help people make informed lifestyle choices to reduce their cancer risk.
We have contributed over $105 million for innovative research conducted at universities, hospitals and research centers across the country. Find evidence-based tools and information for lowering cancer risk, including AICR’s Recommendations for Cancer Prevention, at www.aicr.org.All active news articles