Older Women at Risk of Bone, Muscle Loss With Low-Cal Diets

Liam Davenport

October 12, 2018

BERLIN — Individuals who follow a very low-energy diet to lose weight may experience loss of handgrip strength and bone mineral density (BMD), say Australian researchers, who found the effects were particularly pronounced in older women.

The study of 150 individuals, presented here at the European Association for the Study of Diabetes (EASD) 2018 Annual Meeting, showed that a 2-month low-energy diet followed by a weight loss maintenance program led to significant reductions in handgrip strength in both older and younger women.

Presenter Radhika Seimon, PhD, Boden Institute of Obesity, Nutrition, Exercise & Eating Disorders, University of Sydney, Australia, also said that hip and spine BMD decreased significantly in individuals aged > 51 years, a change that appeared to be driven by reductions in older women.

Seimon told the audience the results suggest that "low-energy diets in females and older adults could benefit from strategies to protect against loss of muscle strength and bone mineral density; for example, using diets that are higher in protein and also exercises such as strength training."

"However, given the known gravity of obesity-related health complications, concerns about potential effects of low-energy diets on muscle strength and BMD should not deter clinicians from using these diets to manage overweight/obesity," she and her coauthors stress. Rather, they should take "due care to monitor and protect musculoskeletal integrity before, during, and after the diet."

Approached for comment, session cochair Angela A. Rivellese, MD, Department of Clinical and Experimental Medicine, University of Naples Federico II, Italy, told Medscape Medical News that the findings "are very interesting."

However, she said "it's a pity" that it is not clear what specific diets and physical activity the participants followed in the maintenance phase "because I think that these factors may influence the outcome relative to bone density and also hand grip."

She continued: "This a very important aspect of the decrease in body weight in the different types of diets...so it's very important to look at these possible effects."

Rivellese believes that individuals with a high level of physical activity, including women, would not experience significant decreases in handgrip strength and BMD, "at least from what we know from other studies."

She added: "one of the answers is to bring together diet and physical activity."

Gender Differences in Handgrip Strength After Very Low-Calorie Diet

Seimon began her presentation by noting that weight loss of as little as 3% to 5% leads to clinically meaningful improvements in health, and that the most effective lifestyle interventions are very low-energy diets.

"These very low-energy diets usually involve severe energy restriction and this is achieved by replacing all, or nearly all, meals with meal replacement products such as shakes and soups," she said.

However, they are underutilized, Seimon added, "possibly due to concerns that very low-energy diets may possibly be associated with adverse effects on body composition, such as reduction in muscle mass, which reduces muscle strength, and a reduction in bone mineral density."

The researchers therefore conducted a substudy of the larger PREVIEW study; the latter was a lifestyle intervention study of more than 2000 individuals, the results of which were published in August, as reported by Medscape Medical News.

In this substudy, there were 150 individuals aged 27–70 years with an average body mass index > 27 kg/m2; the majority (69.3%) were women.

They initially followed a low-energy diet for 2 months and then entered a weight loss maintenance phase involving dietary, exercise, and behavioral changes. The participants were followed up at 2, 6, 12, 24, and 36 months from baseline.

The low-energy diet consisted of four Cambridge Weight Plan meal replacement products per day plus 400 g of nonstarchy vegetables and 1 teaspoon of oil, at a daily energy consumption target of 800 kcal (3400 kJ).

The diet led to a drop in weight in all participants that, although partially attenuated during the maintenance phase, remained significant at all time points versus baseline (P < .05).

The team found that handgrip strength changed differently in men and women during the course of the study.

While men had an initial increase in both dominant and nondominant handgrip that was steadily lost over time, women experienced a significant decrease in handgrip during the low-energy diet period, a reduction that was maintained during the course of the study (P < .001).

When the researchers stratified participants by age, they found that men aged ≤ 51 years had the largest increase in both dominant and nondominant handgrip strength, while men aged > 51 years showed no overall change.

Women aged ≤ 51 years and > 51 years had similar decreases in both dominant and nondominant handgrip strength, which Seimon said were on par with muscle strength loss per decade seen in adults older than 40 years.

Losses of BMD Confined to Older Women

As there were no significant differences in BMD changes between men and women, the team stratified the participants by age.

After an initial decrease, people aged ≤ 51 years experienced a significant increase in hip BMD versus baseline by the end of the study period (P < .01). In contrast, hip BMD decreased significantly in participants aged > 51 years and remained so during follow-up (P < .01).

Spine BMD initially increased significantly in individuals aged ≤ 51 years and then decreased nonsignificantly versus baseline. A similar pattern was seen in those aged > 51 years, although the decrease was significant by the end of the study (P < .001).

Further analysis revealed that the greatest losses in both hip and spine BMD were in women aged > 51 years, with women aged ≤ 51 years and both younger and older men showing largely nonsignificant fluctuations around baseline levels.

Seimon noted that the study may be limited by the researchers being blinded at the time of analysis to the diet and exercise interventions during the maintenance phase, "so therefore we are not able to comment on the effect of the diet and exercise in the different populations."

During the post-presentation discussion, Seimon said that, during the maintenance phase, participants "were allowed to eat ad libitum but they were given direction and advice on portion-size control and what products to eat."

Asked how well the participants adhered to the low-energy diet during the initial 2 months, she said that only people who achieve 8% weight loss during the initial intervention phase were included in the analysis, "so by definition they were compliant."

The authors have reported no relevant financial relationships.

European Association for the Study of Diabetes (EASD) 2018 Annual Meeting; October 4, 2018; Berlin, Germany. Abstract 196.

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