Habitual physical activity is accepted to be the most important lifestyle behaviour for overall health. It plays an important role in the management of body weight and body composition and is therefore a crucial component of both prevention and treatment strategies for overweight and obesity. The benefits of regular physical exercise in obese/overweight individuals are numerous – it improves insulin sensitivity, lowers blood pressure, decreases inflammatory markers, improves mood, may reduce appetite, preserves lean body mass while improving metabolic rate and lipid profile, and reduces the risk of developing other obesity-related diseases. Importantly, physical activity reduces the amount of fat around the stomach area, which is significant given the relationship explained earlier, between abdominal adiposity and cardio-metabolic risk.

However, in addition to the benefits listed above, physical activity of sufficient frequency and intensity also improves cardiorespiratory fitness in overweight/obese adults. Cardiorespiratory fitness is associated with significant health benefits, and these benefits are independent of the health gains associated with weight loss. Improved fitness increases life expectancy even in those individuals that may be carrying a few extra pounds. In fact, some studies have shown that normal weight but unfit individuals could be at a higher risk for mortality than obese but fit individuals. This may well come as a surprise, since the general belief is that being normal weight is synonymous with being healthy. But what these studies emphasize is the imperative of being active and staying fit. Therefore, exercise should be encouraged regardless of body weight or body size, and in the case of weight loss programmes, the goal should be BOTH weight/fat reduction AND improvements in cardiorespiratory fitness.

Recommendations for exercise to manage body weight and composition

Before starting an exercise program, or increasing your training, it is recommended that you go for a full medical check-up. Make sure you discuss any medication you are taking with your healthcare professional, and any other concerns you may have, so that any special medical requirements can be explained and understood in the context of exercise. Thereafter you may also want to consult a dietitian and an exercise specialist to assist you with creating an appropriate strategy for you to achieve your goals.

The American College of Sports Medicine international guidelines suggest that between 150 and 250 minutes of moderate-intensity exercise is needed per week to prevent weight gain of more than 3% of body mass. However, in order to achieve weight loss and then maintain weight long term (i.e. do not regain weight), more than 250 minutes per week of at least moderate-intensity activity may be required. These may seem like unachievable goals at first, but you won’t start by doing these amounts of exercise – this is what you are aiming to get to over time. In another article entitled “Training Principles – Progression and Periodization” we explain how to progress with an exercise programme.  Exercise training that includes both endurance-type activities and resistance training several times a week, is the most effective strategy in promoting fat loss while retaining muscle mass and bone density and reducing abdominal fat. In addition, weight loss is most effective when a physical activity regime is combined with moderate dietary calorie restriction.

For people with a BMI* of 27-35, a general guideline is to aim to achieve a weight loss of 0.2 to 0.45 kg per week.  And people with a BMI* of more than 35, aim for weight loss of between 0.45 and 0.9 kg per week. Continuing at this rate for about six months should result in a 10% body weight reduction, after which further weight loss can be considered if necessary, or weight maintenance becomes the goal. Considerable research shows that even a reduction in 3% to 5% of body weight affords health benefits.

Having outlined the recommendations above, it should be emphasized that weight loss goals and strategies are personal, and the achievement of the best possible body weight for an individual will need to take into account many factors including the individual’s overall health, lifestyle, age, current weight, and how physical activity affects that individual’s body weight and composition.  A fitness professional, in consultation with a dietician and your healthcare professional, will be able to formulate a realistic and individualized plan to help you achieve your weight loss or maintenance goals.

*BMI = weight (kg) / height (m)2
Example:  100kg / (1.85x1.85) = 29.2