Scientific observations across many years, thousands of individuals engaging in regular exercise, and a European fitness industry worth more than €26 billion serve as a clear indicator of the great benefits that being active can do for the human body. However, we must be honest about the fact that exercise for weight loss is not the cure-all panacea that it is often portrayed to be.
The elephant in the fitness room
Perhaps the biggest ‘elephant in the room’ in relation to exercise and fitness is its impact upon weight loss! Exercise for weight loss is promoted as the answer in almost every magazine, blog and exercise video. It is even a major component of many government strategies for overcoming obesity and the world’s ballooning waistlines. It seems that no matter what, exercise attracts all the attention when it comes to answers for weight loss. There is plenty of ongoing debate over dietary factors in terms of how they impact weight loss, but exercise appears to rarely get questioned?
One of the aspects of weight loss that muddies the waters is that most people do not apply a single change when they try to lose weight and lower their body fat. Weight loss usually results from a series of combined changes to an individual’s daily practices. There are many different strategies in the scientific literature that could be applied alongside exercise to help achieve weight loss such as:
- A low calorie, low fat, or low carbohydrate diet
- Increasing protein in the diet
- A high fibre diet
- Reducing sugar intake
- Removing processed food
- Improving sleep
- Reducing stress and increasing relaxation
- Detoxification protocols
- Increasing activities of daily living
- Using weight-loss supplementation
- Lifestyle behaviour changes
- Increasing public/group accountability
- Alcohol reduction etc. etc. etc.
It is rare that exercise for weight loss with no other associated change in behaviour is the strategy of choice. Perhaps that is a good thing too! The scientific evidence is in support of this statement too.
Exercise for weight loss evidence
If you put aside all other ways and focus upon exercise alone as the sole strategy for reducing body weight, it is lacking in punch. Don’t get me wrong it does have a positive effect, but the effect is fairly small! Certainly, nothing like what is proposed across the internet or modern social media channels. In 2006 an independent group of scientists representing the renowned Cochrane Collaboration published a meta-analysis (Shaw 2006) that looked at this very issue…by asking the question, ‘how effective is exercise for managing overweight and obesity?’ The research reviewed studies that only utilised the gold scientific standard of randomised controlled trials (RCT). These RCT’s looked at weight loss periods between 3 to 12 months in duration comparing different weight loss methodology. Here are the facts which summarise their scientific findings on the matter up to 2005:
- General exercise as a lone strategy provided weight loss between 0.5 – 4.0 kg
- Low-intensity exercise as a lone strategy provided weight loss between 0.0 – 6.3 kg
- High-intensity exercise as a lone strategy provided weight loss between 1.3 – 8.9 kg
- Applying diet as a lone strategy provided weight loss between 2.8 – 13.6 kg
- When diet was combined with exercise it provided weight loss between 3.4 – 17.4 kg
- Diet combined with high-intensity exercise provided weight loss between 6.4 – 19.6 kg
Out of the 6 different strategy options looked at above, it is clear that a general exercise programme is the least effective of all the methods applied. High-intensity exercise as a lone strategy does improve things and appears to be about twice as effective as general exercise. However, all three lone exercise strategies fall well short of lone dietary or combined exercise and dietary strategies. The authors of this study provided some very good summary statements which help to bring in a few other considerations than just the factual weight loss ranges shown above:
- These findings are consistent with previous reviews (Miller 1997;McTigue 2003; Douketis 2005) that demonstrate only modest (less than five kg) weight loss with exercise alone as a weight loss intervention, and improved weight loss with diet and exercise compared with exercise alone.
- The results of this study support the hypothesis that vigorous activity is more effective than moderate or light intensity exercise in stimulating weight loss…However, high-intensity exercise was only significantly better than low-intensity exercise at inducing weight loss when undertaken without dietary change. When diet was also modified, exercise intensity did not significantly increase the degree of weight loss.
- Both low calorie and low-fat diets were used as comparison dietary interventions across clinical trials. Both were more effective at facilitating weight loss than exercise alone. This is consistent with the findings of other studies that also demonstrate dietary modification is superior to exercise in obtaining weight loss in overweight and obese adults (Curioni 2005; Hansen 2005).
Exercise is beneficial
You may be thinking that exercise for weight loss is not very helpful and that a diet alone would be best to lose weight? Well, there are other benefits that should not be overlooked in relation to applying exercise as part of a weight-loss strategy. These ‘additional’ benefits certainly warrant the inclusion of exercise in the battle of the bulge. The study authors state:
- Positive effects on CVD risk factors were demonstrated with exercise interventions in overweight and obese adults in this study. Those who participated in exercise interventions alone reduced systolic and diastolic blood pressure, cholesterol, triglycerides and fasting serum glucose. They also increased HDL levels. The changes that were statistically significant compared with no treatment were changes in diastolic blood pressure, triglycerides, HDL and glucose… These changes were independent of significant weight loss. Weight loss does not appear to uniformly improve cardiovascular risk factors, particularly if 5% or less bodyweight reduction (Douketis 2005).
In short, exercise imparts considerable benefits to the cardiovascular system that help reduce heart disease and diabetes risk, even in the face of minimal weight loss. There are also many other benefits from exercise that would literally take a textbook to fully explain. We are not discounting exercise at all. But we need to be honest about its fat burning capacity as a sole strategy – it just is not that powerful! So the real take-home messages of this weight loss science blog are simply:
- Weight loss is best achieved through carefully planned dietary modification combined with the appropriate application of higher intensity exercise methods
- Exercise is very effective at reducing heart disease and metabolic health risk factors regardless of weight loss and as such is a necessary part of a healthy lifestyle