By adding an hour of brisk walking to your daily schedule, you can lose several kilos in 3–6 months, as long as you also eat moderately. The impact of exercise on weight loss is perhaps not as large as you'd imagine when measured in kilos, but it plays a very important role in supporting a lighter diet.
Exercise narrows your waist, and this effect is most visible in your waistline and internal organs. Take two people with the same body mass index – the one who is more physically active and in better shape will have a narrower waist.
Exercise maintains muscle mass as you lose weight – you lose fatty tissue, not muscle. The benefits of exercise also include an increase in HDL cholesterol (good cholesterol), improvements in insulin sensitivity and lower blood pressure.