Obesity surgery, 2, 375-37s

Allied Health Sciences

Maximum Nutrition, Minimum Calories

Georgeann Mallory, RD

Gainesville Surgical Group, Gainesville, Florida, USA.

There is more to losing weight, maintaining weight and choosing a healthy diet after gastric bypass than simply limiting food intake and avoiding sugars. Patients must learn to make food selections that have a high nutrient:energy ratio. Considerable research indicates that the dietary fat level, independent of total caloric intake, is a predictor of fat storage. A contributing factor is the difference in metabolic efficiency of converting dietary fats to body fat compared to the relative inefficiency of converting carbohydrates to body fat. The recommendation that no more than 25% of daily caloric intake come from fat is in keeping with good nutritional practices and may also lower the risk of heart disease and cancer. Patients should have nutrition counseling supplemented with written materials on label reading and recognizing high fat foods, types of fat and cholesterol, serving sizes, meal planning, low fat cooking and dining out. Choosing foods with a high nutrient:energy ratio allows the patient to eat an increased volume and thus a wider variety of foods to meet their nutrient and energy requirements.

Key words: Caloric density, dietary fat, fat metabolism, obesity, weight loss.

Introduction

Gastric bypass is not a passive surgery but requires ongoing patient effort and commitment to attaining and maintaining a healthy lifestyle. It is a tool for the patient to use. Surgery will help the patient with volume control and, secondary to the negative effects of dumping syndrome, play a part in the selection of non-sweet items. There is more to losing weight, maintaining weight and choosing a healthy diet after

Presented in the Premeeting Course ‘Standards of Care’ for Allied Health Sciences at the Ninth Annual Meeting of the American Society for Bariatric Surgery, New Orleans, LA, USA, 10 June 1992. Reprint requests to: Georgeann Mallory, 6717 N.W. 11th Place, Suite C, Gainesville, FL 326054233, USA. Tel: (904) 331-5255; fax: (904) 332-3563.

0 1992 Rapid Communications of Oxford Ltd

gastric bypass surgery than simply limiting food intake and avoiding sugar. This fact should be made quite clear to the prospective patient and continually emphasized during pre- and postoperative counseling.

It has been our experience that patients will stop losing weight at about I year after surgery with an average caloric intake of about 1200-1500 calories for women and 1500-1800 calories for men. If patients are to maintain their weight and their health, they must learn to make food selections that have a high nutrient:energy ratio. For example, skim milk has a higher nutrient:energy ratio than whole milk. Both contain calcium, protein and vitamins A and D, but whole milk has 40% more calories because of its higher fat content.

Dietary fat contributes more than twice as many calories (9 calories/g) as equal amounts of either protein or carbohydrate (each 4 calories/g). Given the greater caloric density of fats compared with other macronutrients, it seems reasonable that caloric intake and body weight would be positively related to the fat level in the diet. A study at Cornell University’ found that when allowed to eat freely, women on high fat diets (45-50% fat) gain weight, on medium fat diets (JO-35% fat) maintain weight, and on low fat diets (15-20% fat) lose weight. The mean daily intakes were 2087, 2352, and 2714 calories for the low fat, medium fat and high fat diets, respectively. They also noted that the women on the high fat diets did consume less food. This volume reduction was not enough to compensate for the increased energy provided by the high fat diet. In a more recent Cornell study,’ 13 women were randomly assigned to either a

low fat diet (2O-25% fat), or a control diet (35-40% fat) for 11 weeks. The women were allowed to eat freely and never knew which diet they were on. This was followed by 7 weeks of no dieting and then 11 weeks of diet opposite to

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their first II weeks. Women on the low fat regimen lost twice as much (2.5 kg) as those in the control group (1.1 kg). The average daily caloric intake was 1800 on the low fat diet and 2100 for the control diet.

Studies indicate that total daily caloric intake is not the only variable that predicts whether fat will be stored but that the percentages of fat, protein and carbohydrate in the diet affect body weight and composition. Research comparing the macronutrient composition of diets suggests that obese individuals consume a greater portion of their energy from fat than the non-obese.3-5 A Stanford study6 examined the diets of 155 obese men and found no correlation between total calories and body fat, total weight or fat-free mass. They did, however, find a negative correlation between obesity and dietary intake of carbohydrate, fiber, and plant protein and a positive relationship between obesity and dietary fat. When overfeeding lean individuals to produce weight gain, researchers7 found that it took more calories and more time when excess calories were provided from a mix of carbo- hydrate and fat than when the excess calories were provided from fat only.

A recent study’ examined the potential long- term impact of low fat diets on body weight changes over 1 and 2 years in 303 women participating in a low fat intervention trial. The intervention group (20% fat) comprised 184 women and 119 were in the control group (39% fat). At I year, fat intake decreased 59%, energy intake 25%, percent energy from fat 45% and weight by an average of 3.0 kg in the intervention group. The control group decreased their fat intake by 12%, energy by S%, percent energy from fat by 4% and weight by 0.4 kg. Using four multiple-regression models that examined the independent effects of change in energy and percent energy from fat on weight change, no significant effects of energy reduction were shown, once the effects of dietary fat were controlled for. This report was the first to use statistical techniques to show a strong association, independent of total energy intake, between changes in proportion of energy derived from fat and changes in body weight in humans.

Prewitt et aL9 studied the effects of diets with various macronutrient contents on body weight and body composition as part of a weight maintenance program in 18 pre-menopausal women. Subjects were fed a control diet (37% fat) for 4 weeks followed by a low fat diet (20% fat) for 20 weeks. Adjustments in energy were made throughout the study to maintain weight. By the

end of the low fat period, energy intake had increased significantly compared to the high fat diet, reaching 119% of the high fat intake. In spite of this, at the end of the low fat diet, subjects exhibited decreased body weight and body fat and an increase in lean body weight.

The differences in how the body metabolizes and stores fat may explain why dietary fats are more ‘fattening’ than carbohydrates when energy provided is a constant. The thermic effect of food (TEF) in the form of carbohydrate is greater than that of fat.” A high carbohydrate meal enhances the TEF of the next meal consumed. In contrast, the TEF declines as the percentage of fat in the diet increases. Since less energy is lost to TEF, more is available for use and storage. It costs less energy to convert and store dietary fat as body fat than it does to convert and store carbohydrate as body fat. Dietary fat can be converted to triglyceride body fat stores at a metabolic cost of 3% of ingested calories while the cost of converting and storing dietary carbohydrate as body fat requires 23% of the ingested ca1ories.i’ Dietary carbohydrates are efficiently stored as glycogen with an energy cost of only 7%, but storage is limited to approximately 500 g.9 Fat stores are in kilograms and can be expanded almost without limit. Carbohydrate is preferentially utilized to replenish glycogen stores. Researchers fed glycogen-depleted and non-depleted subjects high carbohydrate diets and found that once glycogen stores reached a maximum, fat synthesis began.l’ High calorie/high carbohydrate diets will increase fat synthesis and thus body fat because glycogen stores remain filled, but the process is very inefficient and metabolically expensive, and thus such diets cause less weight gain.

The Food and Nutrition Boards Committee on Diet and Health recommends that no more than 30% of caloric intake comes from fat.13 This recommendation is endorsed by the American Heart Association, American Dietetic Association, and the National Cancer Institute. This objective is consistent with good nutritional practices and may lower the risk of heart disease and cancer. Meeting this goal by altering food choices to selections relatively low in fat will help patients meet their nutrient needs while maintaining body weight at the desired level. We encourage our patients to aim for 25% of their total calories from fat.

People sometimes have a tendency to take things to extreme. If a little is good then more is better or if less is good then none is better. Indeed, some people wonder if fat should be spelled with two t’s to make it a four letter word.

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Maximum Nutrition, Minimum Calories

or fat-free foods, i.e. mayonnaise, ice-cream, cakes, salad dressings, are not part of a major food group but are considered extras to be eaten sparingly. They are not good sources of vitamins, minerals, protein, or complex carbohydrates, and care should be taken not to fill up on these foods in place of nutrient-providing foods. One must also remember that fat-free does not mean sugar-free or calorie-free.

Health professionals working with the baria- tric patient play an important role in promoting health by teaching patients how to make informed food choices. Most patients are quite familiar with diets but not necessarily with good nutrition. The newly released Food Guide PyramidI provides a basic pattern for patients to follow and constitutes the foundation of a balanced diet. During the first postoperative year when follow-up is most intensive, patients should have nutrition counseling supple- mented with written materials on label reading and recognizing high fat foods, types of fat and cholesterol, serving sizes, meal planning, low fat cooking, and dining out. In our practice, patients are counseled by a registered dietitian at each office visit where the above subjects and individual needs are addressed and reinforced with educational pamphlets and the Lifelong Behavior Modification Workbook.i4 Continued nutrition counseling follow-up after the first year to evaluate learning and continued application of techniques is an essential factor that needs to be included in the plan. A regular review of diet diaries can reinforce dietary changes. Support groups are another information resource for patients and a source of reinforcement of positive behaviors.

Gastric bypass patients are given a prophylac- tic multivitamin/mineral supplement containing iron such as Centrum, 1200 mg calcium, and either 500 pg vitamin B,, daily by mouth or 1000 pm i.m. injections monthly to compensate for malabsorption of nutrients. However, some essential nutrients do not have established recommended daily allowances and others may not even be known. Therefore, we must rely on the consumption of a variety of foods to provide essential nutrients and adequate energy. The more patients know about nutrition, the wider their array of food choices. Through nutrition counseling and support, patients will be able to implement dietary changes to meet their nutrition needs.

When the subject is fat, none is not better. Dietary fat serves as a carrier for fat-soluble vitamins and provides essential fatty acids. These needs can be met by a diet containing 15-25 g of appropriate food fats. There is no specific requirement for fat as a nutrient in the diet.

There are also no foods that are inherently good or bad because of their fat content; a specific food does not have to be omitted from the diet because more than 25% of that individual food comes from fat. The goal is to limit fat intake to no more than 25% of total calories consumed in 1 day. Combining small amounts of high fat foods with plenty of lower fat selections such as fruits, vegetables, grains, legumes, and low fat cuts of skinless poultry, seafood and low fat dairy products will provide needed vitamins, minerals, protein, and fiber. Any food can fit into a healthful, low fat diet-on occasion, even beef, butter, or eggs.

To calculate a person’s maximum daily fat allowance in grams, multiply total calories by 25% and divide by 9 (9 calories/g fat), e.g.

1200 calories x 0.25 = 300 calories

300 calories/9 calories/g = 23 g.

Although it is not necessary for each and every food consumed to provide less than 25% of its total calories from fat, calculating fat calories for individual foods is a useful tool. If most foods eaten throughout the day contain less than 25% of calories from fat, then the chances of meeting the daily goal are enhanced. It also helps patients to evaluate the nutrient:energy ratio of individual foods and differentiate helpful from misleading information found on food labels.

About 60% of packaged foods currently have nutrition labels that list grams of fat per serving. Some manufacturers label their products with claims such as 80% fat-free, implying the product is 20% fat. This is misleading because the calculation is based on percent fat as percentage of weight, not its total calories. Information on non-labeled foods can be found in various books providing information on calories and fat grams.

To calculate the percentage of fat in a product use the following formula:

fat grams per serving X 9

total calories per serving X 100 = percent fat.

A general rule of thumb to follow: keep fat to no more than 3 g per 100 calories.

There are many fat-free or reduced fat versions of a variety of foods. These foods provide many more choices for the person following a low fat diet. However, the majority of these reduced fat

References

1. Lissner L, Levitsky DA, Strupp BJ, et al. Dietary fat in the regulation of energy intake in humans. Am ] Clin Nutr 1987; 46: 886-92.

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2. Kendall A, Levitsky DA, Strupp BJ, et al. Weight loss on a low-fat diet: consequence of the imprecision of the control of food intake in humans. Am J Clin Nufr 1991; 53:1124-9.

3. Tremblay A, Plourde G, Despres J, et al. Impact of dietary fat content and fat oxidation on energy intake in humans. Am ] Clin Nufr 1989; 49: 799-805.

4. Romieu I, Willet WC, Stampfer MJ, et al. Energy intake and other determinants of relative weight. Am J Clin Ntlfr 1988; 47: 406-12.

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8. Sheppard L, Kristal A, Kushi L. Weight loss in women participating in a randomized trial of low-fat diets. Am

1 Clin Nufr 1991; 54: 821-8.

9. Prewitt TE, Schmeisser D, Bowen PE, et al. Changes in body weight, body composition, and energy intake in women fed high- and low-fat diets. Am J Clin Nufr 1991; 54:304-10.

10. Sims EA, Danforth E. Expenditure and storage of energy in man.1 Clin hesf 1987; 79: 1019-25.

11. Flatt JP. The biochemistry of energy expenditure. In: Bray GA, ed. Obesity Research II. London: Newman

1978: 211-28. 12. Acheson KL, Schutz Y, Bessard T, et al. Nutritional

influences on lipogenesis and thermogenesis after a carbohydrate meal. Am ] Physiol 1984; 246: E62-70.

13. National Research Council. Diet and health: implica- tions for reducing chronic disease risk. Report of the Committee on Diet and Health, Food and Nutrition Board. Washington: National Academy Press 1989.

14. United States Department of Agriculture. Home and Garden Bulletin 249. Prepared by Human Nutrition Information Services 1992.

(Received 9 ]une 1992; accepted 15 ]uly 1992)

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