Low Fat Diets, Aerobic Exercise, and Weight Loss:
How Does It All Fit?
These days it seems that almost everywhere in the media there are claims about the effectiveness of low fat diets and aerobic exercise on weight loss. From billboards, to magazines, to TV, everyone seems to know exactly how to lose weight by eating a low fat diet and /or by exercising on a regular basis. Sample menus and hypothetical exercise routines that are designed to help people lose weight consistently appear in the media, and most come with some type of guarantee that weight loss will follow the "correct and continued use" of the plan. These claims and examples vary from seemingly practical to downright outrageous, with a multitude in between. The problem is that all of these claims and examples are so different from one another the consumer has no way to know which, if any, is the most effective way to lose weight. Is eating less that 15 grams of fat, and exercising 30 minutes each day the most effective way to lose weight? Is eating anything you want, and exercising 90 minutes each day that is the most effective weight loss strategy? Or, is it something completely different? Medical research shows that exercising regularly and eating a well-balance diet that is low in fat can assist in weight loss, as well as provide for better overall health. Finding the best combination of the two is the difficult part.
The weight loss business.
The weight loss business is booming. The idea of a company developing their own strategy for weight loss, and selling it has been a successful one. Companies such as, Weight Watchers (http://www.weight-watchers.com), and Jenny Craig, have become very well known and very economically successful. Each of these companies has its own theories about losing weight, however, the majority of these companies use a combination of a low fat diet and a regular exercise program to promote weight loss. Many also use a support mechanism such as weekly, or monthly group, or individual meetings to help their clients maintain the program. (http://www.yahoo.com/Business_and_Economy/Companies/Health/Weight_Loss/Diets_and_Programs/)
For example, Jenny Craig offers a program that includes daily menus of selected foods, which they package and provide to the client, and weekly counseling sessions with an employee of Jenny Craig. The daily meals are designed to provide a specific number of calories, which is predetermined by the clients weight and self-assessed activity level. Each day includes three meals and a snack that can all be eaten anytime the client chooses. The weekly counseling sessions are the time when the client is weighed to see if they have lost any weight. These sessions are supposed to encourage the client to stick with the daily menus, and not add extra food, and to continue exercising to booster the weight loss process. Usually the suggested exercise is not added as part of the program until the third or fourth week, unless the client already has an exercise routine. The clients are also given guides to eating and exercise that will help them lose weight. This type of program is designed to help the client learn how to plan healthy meals and live a healthier lifestyle. Gradually the client will select provide their own food instead of following the pre-determined menus of Jenny Craig. (http://www.jennycraig.com)
Many of these companies are structured similarly and have many of the same philosophies, and it is probable that most of the recommendations are based on medical research on the benefits of exercise and low fat diets. However, while all can provide specific case examples of success, very few provide actual scientific studies that prove the effectiveness of the program.
See also: http://www.choicediets.com/
How do low fat diets fit?
Low fat diets are a part of all of these weight loss programs. Each diet is designed to provide a low fat, nutritional diet that will help the client lose weight by decreasing their fat intake. The programs usually stress the importance of fruits and vegetables, because they are high in nutritional value, and most have little or no fat. Also stressed is the importance of eating all of the food provided and not adding extra food to the daily menus. Most of the programs attempt to personalize the menus as much as possible. Some let the client choose from a list of food for each meal, and others give the client suggested meals and let them decide which meal should go on which day. Once the client has progressed to deciding what to eat completely on their own each program has some way to measure the amount of fat, the calories, and the nutritional value of each food. The amount of fat in the diet is an essential part to most weight loss programs. Some even claim that low fat diets alone will help clients lose weight.
Low fat diets are not only a part of structured weight loss programs, they are posited to be beneficial to anyone who wants to lead a healthier lifestyle, or lose weight. Some even claim that low fat diets alone are enough to prompt weight loss. Because fat is a concentrated form of calories, people who eat less fat are able to consume more food overall, and still maintain their current weight. Experts recommend that no more that 30% of a day's calories should come from fat. By lowering fat intake to less than 30% of a day's calories most can lose weight, because the energy they spend is greater that the energy they consume. (http://www.ccn.cs.dal.ca/Health/CPRC/nutritn.html)
Maintaining a low fat diet is can also help prevent obesity, which can lead to high blood pressure, hypertension, adult onset diabetes, and heart disease. Low fat diets help to prevent the occurrence of obesity, and the possible occurrence of a number of negative side affects that are associated with it by limiting the fat that the body consumes and consequently the fat the body can store. There are different types of fat that have different effects on the body, but eating less fat overall is the most important concern.
See also: http://www.idahomall.com/fatfacts/
Where does exercise jump in?
Exercise is also an integral part of many commercial weight loss programs. It is often added after the pattern of eating is established so that the client is able to become comfortable with their new eating pattern first. Regular weekly exercise is generally what programs support, with varying degrees of intensity and longevity. Some programs suggest 15 to 20 minutes of cardiovascular fitness 3 to 4 times a week, and others suggest 30 to 60 minutes of cardiovascular fitness 4 or more times a week. Most of the programs also include warming up and stretching as part of the exercise routine. Varying they type of exercise is suggested to prevent boredom, and to work different parts of the body. In any case, exercise is an integral part of weight loss programs.
Exercise not only helps with weight loss efforts, but it also helps individuals to stay physically fit and healthy. Exercise works the heart and lungs, relieves stress, increases lean muscle mass and decreases body fat on a long-term basis, and increases energy levels. Exercise is most effective if it is incorporated into an individual's lifestyle as part of a daily or weekly routine. Intensity and longevity of exercise depends on the individual. People of different ages and with different health factors will need different amounts of exercise to stay in shape. The amount of calories burned during exercise also differs with the individual. The amount of lean body mass a person has helps determine the number of calories burned, the more lean body mass, the more calories burned, and every person has different amounts of lean body mass. (http://www.k2.kirtland.cc.mi.us/~balbachl/cardio.html)
Aerobic exercise has been found to be the most beneficial type of exercise. Exercise promotes growth of coronary arteries which helps blood flow to the heart more easily. It raises levels of HDL, the good cholesterol, in the blood stream, and it lowers blood pressure. Exercise can also help diabetics by removing glucose from the blood, so those that are on insulin need less insulin when they exercise. Exercise relieves stress by reducing muscular tension, and it may reduce levels of adrenaline caused by stress. Exercise is an effective way to lose weight, and to maintain a healthy weight. (http://www.ccn.cs.dal.ca/Health/CPRC/exercise.html)
The most effective exercise maintains the heart rate in the target zone (70-85% of your maximum) for an extended period of time. The most effective way to lose weight is to participate in regular exercise and eat a healthy(low in fat, and cholesterol), balanced diet.
See also: http://www.fureai.or.jp/~hcc/TX/ht/aerobic.html
The big picture.
Both exercise and a low fat diet play a key role in weight loss, as well as in maintaining a healthy lifestyle. Different levels of each are effective for different individuals, because each individual has their own genetic predisposition, and environmental factors to contend with. Limiting fat intake to 30% or less of a day's calories and performing aerobic exercise for an extended period of time, 3 to 4 times a week, is a good plan for attempting to lose weight, and for staying healthy. Some may need more exercise and less fat, and others may be able to get by with less exercise and the same amount of fat. However, exercise and healthy eating benefit everyone, even those who do not need to lose weight.
It is not easy to eat healthy when it is so quick and simple to go to McDonald's for a hamburger and fries. It is hard to make time in a hectic schedule to exercise, since we could watch a movie and relax instead, but these are things that are necessary in order to lose weight, or even in order not to gain weight. There are plenty of modern conveniences that could prevent healthy eating and exercise, if they are allowed to interfere. Commercial weight loss programs, that are designed to help people lose weight, are designed with all of these modern conveniences in mind. These programs help individuals to focus on healthy eating and to limit (but not completely avoid) foods high in fat such as McDonald's, and to incorporate exercise into their lives so that they can be happier, healthier people.
Low fat diets and exercise have been proven to be effective weight loss strategies. Programs that use these two strategies are on the right track to helping individuals lose weight, and will at least provide a more healthy lifestyle for clients, even it weight loss is not accomplished. There are no negative side effects from eating a low fat diet and exercising regularly, unless they are abused and taken to extremes, in which case the principle of the strategies is lost and no benefits can be expected. When used correctly low fat diets and exercise can prevent disease and high blood pressure, and be an asset to attempted weight loss.
Anonymous. (1996) Summary of the Surgeon General's report addressing physical activity and health. Nutritional Reviews, 54(9), 280-289.
Anonymous. (1996) Tips on how to eat less fat: It may lower your chances of getting some kinds of cancer. National Cancer Institute, (4).
Goor, Dr. Ron and Nancy. (1995) Eater's Choice, Houghton Mifflin Company, 2-9.
Goor, Dr. Ron and Nancy. (1995) Choose to Lose: A Food Lover's Guide to permanent Weight Loss, Houghton Mifflin Company.
Haskell, W. (1996). Physical Activity, Sport, and Health: Toward the Next Century. Research Quarterly for Exercise and Sport, 67(3), 37-51.
Johnson, E. (1997) Exercise on the Rise. Kansas City Star, pF3.
Malina, R. (1996). Tracking of Physical Activity and Physical Fitness Across the Lifespan. Research Quarterly for Exercise and Sport, 67(3), 37-51.
Paffenbarger, R. (1996). Physical Activity and fitness for Health and Longevity. Research Quarterly for Exercise and Sports, 67(3), 11-30.
Simopoulos, A.P. (1996). Nutrition and fitness: evolutionary aspects, children's health, programs, and policies. World Review of Nutrition, (3), 24-27.
Simopoulos, A.P. & Pavlou, K.N. (1997) Nutrition and fitness: metabolic and behavioral aspects in health and disease. World Review of Nutrition, (3), 24-27.
Psychology DepartmentThe Health Psychology Home Page is produced and maintained by David Schlundt, PhD.
Vanderbilt Homepage | Introduction to Vanderbilt | Admissions | Colleges & Schools | Research Centers | News & Media Information | People at Vanderbilt | Libraries | Administrative Departments | Medical
|Return to the Health Psychology Home Page|
|Send E-mail comments or questions to Dr. Schlundt|