important menopause information
This topic was discussed in a recent version of NAMS Practice Pearl. The most pertinent studies were reviewed by Dr. Krista Varady, PhD, from the University of Illinois at Chicago.
Here is her assessment.
The cause of midlife weight gain is a combination of the following factors: loss of estradiol, age-related decreases in metabolic rate, and for some women, a more sedentary life style. Approximately 40% of women in menopause in the US can be categorized as obese.
There is so much conflicting information about which diet is the most effective for weight loss. It is difficult for physicians, and very confusing for the average women to know which strategy for weight loss has the best scientific data to back up its efficacy. Plus, the metabolism of women at midlife is very different from younger women, and also different than men, so finding studies specific or our sex and age group can be challenging.
Let’s compare low-fat diets to high-protein diets in midlife women:
Three studies of low-fat diets were randomized and controlled, which provides a high level of significance. In the first study, obese women were restricted to <30% fat, and calories were kept between 1200-2000 per day, depending on their weight. After 12 months, the average weight loss was 8.5%. If you started the diet at 180 lbs., you would lose about 15 lbs. in one year. In another study, a very low fat diet, <15% of calories consumed per day, women lost 7.7% of their body weight in 8 months. In another study, where fat was restricted to 20-35%, and calories restricted to a deficit of 500 calories per day, the participants lost 6.1% of their body weight in 4 months, about 11 lbs. for your 180 lb. women.
The Women’s Health Initiative looked at whether a low fat diet was effective in weight maintenance in mid-life women. In this study, more than 19,000 women were asked to restrict their fat intake to <20%, with no limitation in calories for seven years. In the first year, the women lost an average of 1.7%, but maintained about a 1% weight loss for the next seven years, indicating that fat restriction may be a strategy for long term weight maintenance.
Let’s look at the data for high-protein diets.
High-protein diets are effective in preserving muscle mass during weight loss. In one study, a high-protein low-calorie diet was compared to a low protein, low-calories diet, and both compared to an unrestricted diet. Both low calories groups lost the same amount of weight, 10% in six months. Again for our 180 lb. woman, this is 18 lbs. in 6 months. What was most important was that the difference in muscle mass was measured. The high-protein group last half as much muscle as the low-protein group. This is important because our muscle mass determines our resting metabolism: how many calories do you use up when you are at rest, not exercising. If you lose muscle mass, you require less calories to maintain normal functions, and you will need to restrict more to continue losing weight. Two additional studies had similar findings.
The bottom line was that restricted calories, regardless of protein composition of the diet, resulting in similar weight loss. Muscle mass was better preserved with high protein diets, but bone density was not as well preserved, and the benefit of the weight loss on insulin sensitivity was not as good as would have been expected.
Diets that incorporate fasting have become popular. One fasting day alternates with one day of “feasting” The idea is that on fasting days, caloric intake is limited to 500 calories, either at lunch or dinner. On non-fasting days. there is no restriction on what is eaten. Postmenopausal women lost about 11% of their body weight in 6 months with this regime, about 20 lbs. for our 180 lb. woman. Bone density was not affected by the alternative day fasting regime.
So, how do we compare these regimes. Caloric restriction, whether it be low-fat or high protein results in weight loss. High protein seems to be better for maintenance of muscle mass, but possibly sacrificing some loss of bone. What was not discussed was the effect on cholesterol and insulin levels, and the results if these diets were followed in the longer term.
These studies seem to raise many more questions.
Although all studies led to loss of weight, the rate of weight loss was slower than we might hope. For a person who needs to lose more than 20 lbs., it seems that a long-term strategy needs to be used. Rather than dieting, a lifestyle change might be a better approach. Increasing exercise and physical activity gradually can prevent injuries, and finding varied activities that are truly enjoyable may lead to a sustainable program. Incorporating short-term goals that are more easily obtainable may be more effective than going for the 50 lb. weight loss that will take several years to accomplish. Self-monitoring with diet apps that measure the caloric and nutritional value of foods can help to determine if your fat and protein intake are where you want them to be, and to understand the caloric value of portion size and the detriment of snacking and grazing. Many women do well with the structure of programs like Weight Watchers. A nutritionist may be helpful to organize a program individual to your lifestyle and personal preferences.
Unfortunately, long term success with sustained weight loss can be very difficult to obtain.
What is needed is more studies in women after menopause to understand their unique hormone issues how this changes metabolism, and which strategies provide the best success.
Marilyn Jerome, MD
Foxhall OB-Gyn Associates
NAMS Practice Pearl: Dietary Strategies for Weight Loss in Midlife Women, Krista A. Varady, PhD. released December 20, 2017