Evaluating the effects of weight changes and physical activity on mortality in patients with coronary artery disease

This study investigated the effects of changes in body mass index, or BMI (measurement of weight that takes height into account) and physical activity on mortality in people with coronary heart disease (CHD). It was determined that high levels of physical activity reduced the mortality risk. It was also found that weight loss increased the mortality risk, while weight gain reduced it, in people who had a healthy BMI, but not in those who were overweight or obese.

Evidence suggests that obesity plays a role in the development of CHD. It is therefore recommended that people with CHD are physically active and maintain a healthy weight. However, more recent evidence indicates that, in people who already have CHD, a BMI outside the ‘healthy’ range may be associated with lower mortality. However, this is not fully understood, and it is not seen in individuals with a high level of physical activity. Furthermore, very few studies examine the long-term effects of weight changes.

3,307 adults with CHD participated in this study. They attended a clinical examination and filled out detailed questionnaires about their health and lifestyle. They were divided into three groups based on physical activity. The ‘inactive’ group reported no physical activity. The ‘low physical activity’ group reported physical activity below the recommended level. The ‘high physical activity’ group reported physical activity at or greater than the recommended level. The participants were followed up for 30 years for changes in weight, physical activity, and mortality.

Compared with having a stable BMI, participants who lost weight had a 30% higher overall mortality risk. However, this was only seen in participants who had a healthy BMI at the start of the study. Weight gain was also associated with a 25% lower mortality risk in these participants. In overweight or obese participants, neither weight gain nor weight loss affected the mortality risk. 

Compared with inactive participants, participants with low physical activity had a 19% lower mortality risk. Those with high physical activity had a 36% lower mortality risk. The cardiovascular mortality risk was 38% lower in those who maintained a high level of physical activity. The cardiovascular mortality risk was 32% lower in those who changed from inactive to high physical activity.

The study concluded that in people with a healthy BMI, weight loss increased the mortality risk, and weight gain decreased it. The mortality risk was unaffected by weight changes in people who were overweight or obese. However, high levels of physical activity were also found to reduce the mortality risk.

The data on physical activity was self-reported by the participants. Data collected in this way is not always reliable. The study did not distinguish between intentional and unintentional weight loss. This may have affected the results. Furthermore, the effects of weight changes in underweight individuals were not examined.

Discuss the effects of weight changes and physical activity with your physician. It is always important to check with your physician before starting a new exercise program or increasing the intensity of a previous program.