Between the ages of 40 and 80, an estimated 30 to 50 percent of muscle mass is lost, resulting in lower strength and less ability to carry out everyday tasks. This process is known as sarcopenia and it is common and clearly linked to frailty and poorer health in older people.

The associated health care costs are substantial so it is has been a topic of considerable study but the effects of diet on exercise to prevent muscle loss in later life have been inconsistent.  A new review won't clear that up but it least narrows down the problem in studies. Basically, as is always the case in nutrition and diet supplementation claims, be more skeptical than ever. Exercise and a proper diet won't be bad things but there is no magic formula that someone can sell you in a book, any more than eliminating wheat or sugar is a cure for more than a tiny population of people.

The review in Clinical Interventions in Aging looked at combined diet and exercise training trials in men and women aged over 65 years old. Almost 5,000 scientific articles were screened, with more than 100 reviewed in detail and 17 of these were included in the review. 

Professor Sian Robinson of the Medical Research Council (MRC) Lifecourse Epidemiology Unit at the University of Southampton, who led the review, says, "Poor diets and being physically inactive are common in older age. Understanding the benefits of maintaining sufficient levels of physical activity and diet quality to prevent sarcopenia is therefore a priority. Although some studies have found enhanced effects of exercise training when combined with diet supplementation, our review shows that current evidence is incomplete and inconsistent. Further research to determine the benefits of supplementation and exercise training for older people is therefore needed."  

Funded by the Medical Research Council.