A caloric deficit of approximately 3,500 calories (kcal) is needed to lose 1 pound (lb) of body fat. If your goal is to lose 1 to 2 lb per week (a reasonable goal for most overweight individuals), this would require a caloric deficit of 500 1,000 kcal each day! For most people, this would mean 30 to 60 minutes of intense exercise daily. Unfortunately, most American adults are extremely sedentary with about one third getting no physical activity and most people becoming less and less active as they age (exactly the opposite way that the trend should be heading).
More striking is the fact that the benefits of exercise can easily be offset with inappropriate food choices. It is easy to see that the amount of energy expended during 30 minutes of walking can easily be offset with a handful of potato chips, a slice of pizza, or six to eight Oreos! This should not scare one into avoiding these foods at all costs, but it should be recognized that all of us need to consider our “calorie budgets” very carefully.
So, how much physical activity is needed to (1) prevent weight gain and (2) promote substantial weight loss? This is not an easy question to answer, especially considering that exercise will have different effects on appetite and food intake in different people. However, most people will find that their food intake and hunger will not increase much when they begin exercising. In one study, women who had lost weight were followed over the subsequent twelve months. The threshold level of physical activity required to prevent weight regain (less than 10 lb) corresponded to approximately 80 minutes of brisk walking per play. People enrolled in the National Weight Control Registry (NWCR) report a similar level of walking (the NWCR is a large database of individuals who have maintained a 30 lb weight loss for at least one year). In addition, recent data from Japan suggest that accumulating 12,000 to 16,000 steps per day reduces the risk of weight gain. Thus, using a pedometer to track your daily step totals may provide feedback as to whether you are reaching an activity level high enough to help manage your weight.
It is essential to remember that it is total daily energy expenditure that is important. If you increase your daily amount of exercise, but become more inactive during other parts of the day, the impact of exercise on body will be minimized. Perhaps the best strategy is to increase the amount of daily planned physical activity (e.g., add a 15 to 30 minute walk at lunch or in the evening), but to also increase your amount of unplanned physical activity (e.g., take the stairs instead of the elevator, avoid escalators, park your car a few blocks from work).