Which matters more – diet or exercise?

To lose 1lb per week, you need to create a 500 calorie deficit per day. This can be achieved through eating less or moving more, or a combination of the two. So the question is – is it best to eat less or move more?

For most people, consuming 500 fewer calories each day is much more realistic and sustainable than trying to burn off 500 calories per day. Think about how easy it can be to eat 500 calories – grab a large milky coffee and a slice of cake and you're there. But to burn off 500 calories would, for example, require us to do one of the following:

• Run at 6mph for 60 minutes
• Swim front crawl at a moderate intensity for 60 minutes
• Do a vigorous spinning class for 40 minutes

On top of this, the physical demand of burning an additional 500 calories through exercise each day is pretty big. Unless you're a full-time athlete, not many of us could commit this time every single day. We also need rest days from exercise to allow our body time to recover, so burning this number of calories each day through activity would not be sustainable.

Another consideration is the impact lots of exercise has on our appetite. Doing a significant amount of exercise every day can make us feel hungrier which could mean we end up eating more calories and cancelling out some of the calorie burn. Not to mention there is evidence to suggest that many people subconsciously eat more when they're being very active as a way to compensate for the extra energy used (1).

What about when it comes to our health? There's no denying regular exercise is extremely beneficial to our overall health. It helps to strengthen and improve our cardiovascular health, bone density and muscle strength to name a few, as well as boosting our overall mood and sense of well-being.

Research has also shown that individuals who are overweight can significantly improve their health through regular exercise, even in the absence of any weight loss (2). What we find is that regular physical activity can help improve various elements of our health from better blood sugar control, to reduced cholesterol, and even improvements in mental health. This shows how important exercise is in isolation, regardless of weight status.

But is exercise alone enough to counteract poor dietary choices?

Sadly, it doesn't seem so. There is anecdotal evidence that even very active, healthy-weight individuals can suffer the health consequences of an unhealthy diet (3). There are cases of individuals who run miles and miles each week and maintain a healthy weight, but indulge in a diet rich in saturated fat, salt and sugar, who suffer with health issues related to poor diet such as heart disease and diabetes. It's even been reported that as much as 40% of people with a healthy body weight may have some level of metabolic abnormality (4). This again highlights the importance of a healthy diet on overall health status.

Conversely, a well-balanced diet which is also calorie-controlled to help maintain a healthy weight is proven to benefit our health. Eating a diet rich in important nutrients such as protein, fibre, good fats, calcium and other vitamins and minerals, but low in saturated fat, free-sugars and salt, helps to ensure our body receives all the nutrients it needs to function at it's best, without burdening it with excessive amounts of less desirable nutrients.