The foods we eat have a greater influence on weight loss. If you look at the graphs below you can see how physical activity accounts for a relatively small portion of energy expenditure in all but the most active of individuals whilst the energy we take in is entirely dictated by the foods and drinks we consume.
Energy In
Energy Out
This means it would be far more efficient to focus our attention on consuming less than burning more when it comes to weight loss.
In no way does this dismiss the value of exercise. For sure it can contribute to weight loss but its primary benefit is enhancing our muscular system and improving physical performance such as strength, stamina and flexibility. Importantly exercise, particular high intensity exercise like resistance training can also influence the type of weight which is lost from our body.