As a physician and fitness professional I regularly evaluate people who want to lose weight and have often been asked whether diet or exercise is more effective in helping them to reach their goals.  If I had to choose which type of weight loss strategy was more important, I would say that about 80 percent depends on diet.  In fact, research has shown that the majority of weight loss programs which focused on dietary changes produced 2-3 times greater weight loss than programs focused on exercise.  However, long term management of weight loss can be optimized by a consistent exercise program. 

The fact is that most people are prone to consuming foods which contain large amounts of fat, hidden sugar and salt, and preservatives.  Quite often the portions consumed at one sitting are so large that the body ends up in storage mode which can lead to weight gain.  By becoming aware of the value of nutrient-dense foods and re-patterning one’s eating habits so that such foods form the foundation of a daily meal plan, long-term weight loss and maintenance of a healthy weight can be accomplished.  However, the media pushes “quick fixes” by promoting severe caloric restriction and plans which are nutritionally unbalanced, thus creating a state of malnutrition.  For this reason I discourage fad diets as they almost invariably cause rebound weight gain to occur.  There are also different types of pills which by various mechanisms can assist in weight loss.  However, a number of such products can have deleterious adverse effects and should be taken with caution, if at all.  I do make an exception with thermogenics, which, if used properly, can serve as an effective aid in weight loss. 

But what about exercise?  It is true that exercise can often stimulate hunger, but it also boosts metabolism, has a positive effect on brain function, and builds muscle.  There is also some evidence that intense exercise may lower levels of ghrelin (an appetite stimulant) while raising levels of peptide YY (which suppresses appetite).  In other words, if you plan to incorporate exercise into a weight loss regimen (and I highly suggest that you do), make sure to engage in workouts which are intense and challenging.  One caveat:  the aforementioned satiating effect on hunger is short-lived, so don’t be surprised when your body begins to crave food in an effort to replenish depleted energy stores.  Before you begin to think that exercise is a bad idea when trying to lose weight, consider this: apparently, frequent exercise restores sensitivity to brain neurons that control satiety, thus placing you more in tune with your hunger signals. 

Over the long term, the combination of smaller, more frequent meals, nutrient-rich foods and regular exercise can act as an insurance policy of sorts which will protect your weight loss or weight maintenance efforts.