Weight Loss and Physical Activity

by Bruce Rector, M.D.


Increasing one's level of physical activity is an essential part of a complete weight loss program. Physical activity, however, must be combined with dietary modifications in order to lose significant amounts of weight. The most important benefit of physical activity may not be short-term weight loss, but long-term weight maintenance. Patients who continue to exercise after their initial weight loss are more successful at keeping the weight off. It is important to choose activities that you enjoy and can easily incorporate into your lifestyle. Remember that the changes you need to make to lose weight and keep it off are not temporary -- they are long term lifestyle changes.

Weight Loss Formula

The formula for losing weight is very simple. To maintain your current weight, you need to balance the amount of calories you eat with the amount of calories being used by your body. In order to lose weight, you either need to decrease the number of calories you eat or increase the amount of calories you burn. In order to lose one pound of weight, you need to decrease your calorie intake by 3,500 calories. This means that if you want to lose one pound a week you either need to decrease the calories you consume by 500 calories a day or increase the calories you use by 500 calories a day. For most people, combining both strategies is the easiest way to reach their goals. Slowly increasing the amount and intensity of physical activity while cutting back on the amount you eat will result in weight loss. An added benefit of physical activity is that it can increase the amount of calories your body burns even when you are not exercising. For many people, physical activity actually suppresses their appetites and allows them to gain control over their eating.

Health Benefits of Physical Activity

There are many important health benefits, both physical and psychological, associated with increasing physical activity. If done at an appropriate level, physical activity can help decrease the risk of cardiovascular disease, lower blood pressure, improve blood sugar control in diabetics, lower cholesterol levels, and prevent osteoporosis. Increasing physical activity can also reduce stress levels and provide an increased sense of well being. The American College of Sports Medicine recommends that to obtain these benefits, at least 30 minutes of moderate physical activity should be accumulated over the course of the day. It does not have to be done during one continuous session. Furthermore, activities such as walking and taking the stairs instead of using the elevator contribute toward the 30 minutes.

Getting Started

Set Realistic Goals
No matter what your current level of physical fitness is -- couch potato, occasional athlete, regular exerciser -- you can increase your level of physical activity. The key is to start slowly and set realistic goals for yourself. Consistency is the most important thing in starting a program. The health benefits that come from increasing physical activity come from maintaining this activity.

A trap that many people fall into is setting unrealistic short-term goals. They get up one morning and decide to run a certain distance and realize half way through that they cannot do it. They get very discouraged and quit. A more realistic goal for that person may have been to walk for ten-to-fifteen minutes six days/week. They then should slowly increase the amount of time they walk and/or their pace.

Choosing An Activity
When discussing "exercise" programs for weight loss and weight maintenance, I prefer the term "physical activity." For many people when they hear the word "exercise" they start thinking about gyms filled with bodybuilding equipment and stairmasters. Of course, if you enjoy these types of activities they are a great way to increase physical activity. But for many people, there are other activities which may be more appropriate and which they may enjoy more. The activities you choose might include, for example, walking, gardening, swimming, basketball, bowling, or shoveling snows.

The important thing is to choose activities appropriate for you--ones that you can enjoy and that match your current level of physical fitness. Once you start, you can work towards building up the amount of time dedicated to physical activity and improving your level of fitness. Remember, the goal is to participate in physical activities for 30 minutes a day at least 6 days out of the week.

Stay With the Program
A key to continuing with any physical activity program is to make it as enjoyable as possible. Nothing takes the enthusiasm out of a physical activity faster than blisters and sore, tight muscles. Therefore, wear appropriate, loose comfortable clothing, and buy a good pair of shoes if you are walking or running. Also, spend a few minutes stretching your muscles lightly before and after physical activity.

Physical activities can be done in groups or with buddies. Finding a walking buddy can make it a more enjoyable experience and can help provide motivation and support.

Finding Time
Time is a big issue for many of us. How do you find the time for physical activity? Try to incorporate physical activity into your everyday activities. Instead of taking the elevator, take the stairs; instead of parking right next to the entrance of your office, park farther away and walk; take a walk at lunch rather than going to the cafeteria; get rid of the remote control and get up to change the channels. All these things add up! The key is to be consistent and to increase the amount of calories you burn every day.

Calories Used In Physical Activity

Your current level of weight should also be taken into account when planning a physical activity program. The more you currently weigh, the more energy it takes to do the same activity, as compared to someone lighter.

Level of Exertion

Many people are interested in activities that preferentially burn fat. There is a great deal of misinformation in this regard. It is true that your body uses different sources of energy (fat vs. carbohydrates vs. protein) depending on your level of physical exertion. Exercise at a low-to-moderate level of intensity (65% of maximum heart rate) burns fats at a higher percentage. Raising the intensity to moderate-to-high levels (75% of maximal heart rate), the body will prefer to burn carbohydrates over fat. Therefore, many people reason that they should then exercise at low levels of intensity to increase the amount of fat they burn. The problem with this line of reasoning is that by exercising at a low level of intensity, you will use less total calories. Even though the percentage of calories lost from fat will be higher, the total amount of fat used will be substantially less. In order to burn the same number of fat calories at the lower level of intensity, you would need to increase the total amount of time you spend performing this physical activity.

When you are first starting an exercise program, a moderate-to-high range of activity may not be possible. As your fitness level improves, you will be able to increase your intensity and expend more energy. If your focus is weight loss, the higher intensity exercise is preferable.

Resistance Training

As you lose weight, a proportion of the weight you lose will be from muscle. It is important to maintain muscle mass. Besides being important for your level of strength, muscle is a metabolically active tissue. This means that even at rest, muscle is using more energy than other tissues. If you lose muscle, you will need to decrease your calorie intake even further to continue to lose weight and to maintain weight loss.

Resistance training using weights can play an important role in your overall weight loss program. Weight training can be very important in maintaining muscle mass. It also improves strength and appearance, both of which can provide a great deal of motivation and encourage a person to maintain their physical activity program.

Weight Loss vs. Weight Maintenance

I would like to stress again the importance of physical activity in maintaining weight loss. Most people who try to lose weight end up gaining most of the weight back. The best way to keep the weight off is to continue a physical activity program even after the initial weight loss program has ended. Numerous studies have shown that that people who keep their weight off are the ones who continue with physical activity programs even after their diets are over.


Increasing physical activity is only one component of a weight loss program. Exercise by itself will not result in meaningful weight loss unless it is combined with dietary changes. In choosing physical activities and setting activity goals, remember that consistency is extremely important. Consistency is what will provide you with the important long-term benefits from the physical activity. Chose activities that you enjoy, start slow and increase your intensity as you are able.

Increasing physical activity needs to be a lifelong lifestyle change. Although it is an important part of a weight loss program, physical activity is even more important in keeping the weight you lose from coming back. The benefits from physical activity do not end at weight loss. They include increased emotional well being, increased strength, increased endurance and most of all, improved overall health.

As always, before starting a vigorous physical activity program, consult your physician.

Dr. Bruce Rector is a health communications specialist, focusing on effectively delivering important health information to both medical professionals and consumers. He is the Medical Director for an international medical communications company developing educational programs covering a broad range of clinical topics. Dr. Rector has a special interest and extensive experience in the area of weight loss and physical fitness. Dr. Rector attended medical school at the University of Minnesota Medical School where he was a leader in the American Medical Students Association. He did post graduate training at Virginia Mason Medical Center in Seattle, Washington and at Northwestern University Memorial Medical Center in Chicago, Illinois.

Copyright © Bruce Rector. Permission to republish granted to Pregnancy.org, LLC.