Obesity is now a worldwide epidemic and the number of people in the U.S. who are either overweight or obese is greater than the number of normal or underweight people.1,2 Historically, it was felt that obesity was a consequence of gluttony and that obese people merely lacked willpower.

It's now known that weight gain is a complex issue, with genetic and environmental factors involved, as well as behavioral challenges. Despite recent breakthroughs in identifying the responsible genes, enzymes and hormones involved, the problem continues to grow.3  Attempts to create a safe and effective weight loss drug have met with limited success.4 Sadly, few public resources have been allocated to documenting simple behavioral approaches to combat weight gain or promote weight and fat loss.5

Burn More than You Consume: Old News
The overstated adage, "You have to burn more calories than you consume," does little more than point out the problem for the obese. Finding ways to follow that seemingly simple command are necessary in order to achieve any weight loss success. That short statement actually has two parts, burning more calories and consuming fewer. Ironically, as society advances, it becomes increasingly difficult to do either. This article focuses on a simple means of following the second directive, consuming fewer calories.

Food surrounds us, but this has not always been the case. Prior to the second half of this century, living conditions were very harsh compared to the relative luxury experienced today. Outside the U.S., many countries are seeing obesity rates reach epidemic proportions for the first time, as the Western lifestyle works its way into developing nations. The ready access to cheap, high-fat, high-calorie meals has created an atmosphere well suited to overconsumption.

The American obsession is to select large portions of high-calorie foods, with many meals exceeding over 1,000 calories. Experts urge people to consume a variety of whole foods, particularly fresh fruits and vegetables, whole grains and low-fat dairy products. This conflicts with the marketing pressures that tempt people with the opposing promises of flavor and aroma and offer fatty selections, relying on refined flour, starchy potatoes or fried breading. Confused and frustrated, most people make their food selections based on convenience or cost, and let's face it, there are many more fast food drive-throughs than discount farmhouses.

In the course of a normal day, there seem to be few options open to most people. Work schedules and time demands require fast, simple meals during the day. For home-prepared meals, however, there's little difference in the effort required to prepare a small meal versus a larger and more satisfying meal. Creating a "food environment" solution that is practical requires that it be cheap and easy, can be carried around or used "on the go," and doesn't leave a mess. It must also be nutritious.

A practical solution has existed for a number of years and is well known to many athletes. This simple, cheap, convenient and nutritious solution is a meal replacement product (MRP). MRPs may exist as pre-mixed shakes, powdered shake mixes or individually wrapped bars. There are a number of arguments both for and against the use of MRPs as part of a fat loss regimen. While all opinions are valid, some arguments are not legitimate when considered more objectively.

Arguments Against MRPs
Opponents to the use of MRPs often cite the following arguments: MRPs are not natural, do not replace whole food, are not nutritious, taste bad and do not aid in weight loss. Unfortunately, these opponents, while well meaning, are largely misinformed.

MRPs are not synthesized within a factory from large vats of chemicals. Rather they are prepared from natural food products. Typically, the original product, milk for example, is dehydrated, filtered and fortified according to the manufacturer's needs. The product may then be blended and either reconstituted (adding water back in) to make a pre-mixed shake or the batter for an MRP bar, or packaged and processed for sale as a powdered concentrate. These same processes are used in a variety of "natural foods" including breakfast cereals, soda, yogurt, soups, etc. The MRP holds an advantage over most foods in that the shelf life is much longer, so bulk quantities can be purchased and inventories can be better controlled.

Dieticians passionately argue that MRPs do not replace whole food within the diet and they are correct. Whole food, particularly from a balanced diet including fresh fruits and vegetables, provides a number of factors that are not available in MRPs. Phytonutrients are chemicals within plants that provide health benefits. While we are aware of the need for many of these, such as  common vitamins and minerals, we only recently aware of others, and there are still plenty that have not yet been identified. MRPs should complement whole food within a structured diet program, not replace whole food. The purpose of the MRP is to provide the known essential nutrients without the burden of a large number of calories.

MRPs have evolved from blends of dextrose and milk powder. Products that are currently available are usually fortified with vitamins and minerals. Many include newly discovered phytonutrients, such as lutein or lycopene. Most MRPs provide between 50 and 100 percent of the USRDA of the essential vitamins and minerals. Some nutrients that may not otherwise be part of a normal diet, such as essential fatty acids, are included in some MRPproducts.
The original MRPs were horrid tasting; that cannot be argued. However, flavoring ingredients are now added to create a variety of flavors to choose from. The list is more exotic than a tropical garden, with banana, kiwi, raspberry, blueberry and many others joining the traditional favorites of chocolate and vanilla. The technology involved in the manufacture has also made MRPs much more enjoyable, as the proteins are more gently processed and lower heats are used, removing any chemical taste or aftertaste.
As to the argument that MRPs do not aid in weight loss, research has been published on long-term studies in large groups of normal people, not bodybuilders or athletes, proving that MRPs can aid in weight loss.1,6-9

 Arguments for MRPs
There really is not a strong outcry promoting the use of MRPs in the battle against obesity. Sadly, this neglects the potential for introducing a practical solution to millions of people struggling to lose weight. MRPs can complement other weight loss strategies, providing a sense of control to the obese and overweight.

MRPs, as described above, are a nutritious, enjoyable means of controlling food selection and calorie intake. Recall that the experts are urging people to burn more and eat less. Many dieters try to eat less by following one of two methods: skipping meals or eating "healthy" foods.

Skipping a meal seems like an obvious solution. Unfortunately, studies have shown that obese people who skip one meal often overcompensate during the following meal.1 Avoiding the bagel and cream cheese in the morning saves time and gives the dieter a sense of control as food (viewed as a bad thing) is rejected by choice.

Unfortunately, later in the day, when willpower is less, hunger pains are overwhelming and social signals are pressuring the dieter, more food is consumed than would have been, if breakfast had been eaten. It's important that people learn portion control and steps to prevent the appetite from causing binge-eating behavior. MRPs may assist with this, as they can be formulated to provide a sense of satiety (fullness) for several hours, so the next meal is not destined to become a binge nightmare at a buffet line.
Most dieters have one or several books on the "right" foods to eat, with paper clips and bookmarks indicating the underlined pages with the salad bar condiments and dressings. It's too bad that choosing the "right" foods has not been the answer for most dieters.1 To begin with, very few people measure portions. The portions used in the calorie-counting books are not realistic, as most restaurants, cafeterias and vendors know that fullness and satisfaction- not small, low-calorie selections- guarantee repeat business. A tuna sandwich may be listed as having 400 calories and three grams of fat in the book, but the owner of the "Tubby Subby" knows he sells more if he loads on the cheese and mayonnaise, building the sandwich up to 900 calories.

Using the MRPs
While MRPs may not help with food selection when whole food meals are consumed, they can provide a specific amount of calories, as well as providing a healthy blend of the macronutrients- carbohydrates, protein and fat.
Liquid diets have been used clinically to promote weight loss in the hospital or clinic for many years. These diets are not used commonly, as they restrict the person to a very low number of calories, perhaps 800 per day. Weight loss is rapid, but often there are signs of stress upon the vital organs and the weight returns when the diets end.10

Rather than trying to effect rapid weight loss with hospital-based, all-liquid diets, researchers are now evaluating self-managed weight control using MRPs once or twice a day, along with a balanced diet. Four studies, ranging from one to five years, have shown that the inclusion of MRPs with nutritional counseling and support, is a safe and effective aid to weight loss.1,6-9,11 In addition to losing an average of 10 percent body weight, participants also realized several health benefits from the weight loss. A number of positive changes were noted in the lab studies performed, including lower total cholesterol, LDL-cholesterol, insulin, blood pressure and triglycerides. Reducing each of these factors decreases the risk of serious health problems, such as heart disease and stroke.

Beyond providing significant weight loss and improving the health of the participants, the MRP-associated diet program allowed most participants to maintain the weight loss for the duration of the study. This is a valuable finding, as many dieters have experienced weight loss with other programs, only to regain the excess weight upon returning to "normal" eating. MRPs, in addition to aiding in weight loss, are an important tool in allowing people to self-manage their dietary habits and control the "food environment."

There are numerous MRPs available at most grocery stores and nutrition centers. Finding an MRP that fits the budget and tastes good can be easily accomplished with a little experimenting. While there's no defined nutrition profile for weight loss MRPs, attention should be paid to ensure that an MRP is not high in calories. They should be between 200 and 300 calories per serving, fortified with the essential vitamins and minerals (usually 50- 100 percent USRDA) and provide a balanced blend of carbohydrates, protein and fat. Using an MRP in a well-planned diet program may provide the necessary support needed for safe, effective and enduring weight loss.1

  References  
1.    Ditschuneit HH, Fletchner-Mors M,  et al. Metabolic effects of a long-term dietary intervention in obese patients. Am J Clin Nutr 1999 Feb;69(2):198-204.
2.    Fairburn CG, Kelly DB. Eating Disorders and Obesity, 2nd ed. The Guilford Press, New York, 2001.
3.    Jeffrey RW. Public health strategies for obesity treatment and prevention. Am J Health Behav 2001 May-Jun;25(3):252-9.
4.    Cannistra LB, Davis SM, et al. Valvular heart disease associated with dexfenfluramine. NEJM 1997 Aug 28;337:636.
5.    Levy AS, Heaton AW. Weight control practices of U.S. adults trying to lose weight. Ann Intern Med 1993 Oct 1;119(7 Pt 2):661-6.
6.    Ashley JM, St Jeor ST, et al. Weight control in the physician's office. Arch Intern Med 2001 Jul 9;161(13):1599-604.
7.    Fletchner-Mors M, Ditschuneit HH, et al. Metabolic and weight loss effects of long-term dietary intervention in obese patients: four-year results. Obes Res 2000 Aug;8(5):399-402.
8.    Heber D, Ashley JM, et al. Clinical evaluation of a minimal intervention meal replacement regimen for weight reduction. J Am Coll Nutr 1994 Dec;13(6):608-14.
9.    Rothacker DQ. Five year self-management of weight using meal replacements: comparison with matched controls in rural Wisconsin. Nutrition 2000 May;16(5):344-8.
10.    Snow JT, Harris MB. Maintenance of weight loss after a very-low-calorie diet involving behavioral treatment. Psychol Rep 1995 Feb;76(1):82.
11.    Rothacker DQ, Staniszewski BA, et al. Liquid meal replacement vs. traditional food: a potential model for women who cannot maintain eating habit change. J Am Diet Assoc 2001 Mar;101(3):345-7.