Fat replacers have facilitated the development of reduced-fat and fat-free foods that have the taste and texture of high-fat foods, but with less fat and fewer calories. The food industry provided a variety of low-fat products, and a segment of the public responded by consuming them. Julie M Jones and Satya S Jonnalagadda, PhD, explore the options on the table
Obesity rates for both children and adults have increased dramatically in the US, the UK and Western Europe.1,2,3 The epidemic is fuelled by readily available, inexpensive food, especially energy-dense, high-fat foods and increased portion sizes, which both lead to the over-consumption of calories.4,5,6,7,8,9 Because increases in the energy density of foods have also been shown to increase energy intake, it is reasonable to assume that ingestion of foods that lower energy density by any means, including the use of fat replacers, would result in lower overall food energy intake.10,11,12 Thus, manipulation of the energy density of the diet can lower energy consumption by 20-25 per cent, and can lead to modest changes in body weight.13,14
These data indicate that a reduction in the proportion of fat in the diet by 10 per cent can result in a corresponding reduction of 238kcal/day of total energy intake, and can produce a weight loss of -3.2kg. Therefore, lowering the fat content of foods by using fat replacers has potential for lowering the energy density of foods, which can be helpful in the struggle to maintain a healthy weight.15
Fat replacers and their uses
Fat replacers are called by many synonyms with various nuances in their usage. (See sidebar, below.) Fat replacers in food must do two things if they are to help consumers with weight loss. First, they must replicate all or some of the functional properties of fat and, in so doing, impart the sensory properties attributed to fat such as a rich, creamy mouthfeel and a tender texture. No one fat replacer is likely to provide all the functions of fat, such as flavour, texture, lubrication, keeping quality, volume or heat transfer.
Second, they must lower the fat and calorie content of the food. They do this either by enabling the holding of air and water or by being less well absorbed. Fat replacers are most frequently used to replace fat in products with a high fat content, and are used in a variety of food products including frozen desserts, processed meats, cheese, sour cream, salad dressings, snack chips and baked goods. At the height of the interest in low-fat foods, more than 1,000 fat-modified foods were introduced, with fat-modified snacks being the fastest-growing category of products in supermarkets at the time.16,17
Categories of fat replacers
There are three broad categories of fat replacers on the market. Because fat replacers may contain calories, food manufacturers using they should ensure that the final products are not only reduced in fat, but also reduced in calories. In the end the food with fat replacers will be of little value for weight reduction if it fails to cause a significant reduction in calories.
Carbohydrate-based fat replacers: These use carbohydrate polymers and dietary fibres, such as cellulose, dextrins, maltodextrins, polydextrose, gums, fibre and modified starch, to replace fat. Carbohydrate-based fat replacers can provide up to 4kcal/g if the carbohydrate is fully digestible. Often the calories are even lower because the fat replacers are either dietary fibres, which are not digested or only fermented to some degree, or digestible carbohydrates mixed with water so they provide 0-2kcal/g. In some cases fibres, such as cellulose, are ground into microparticles that can form gels for use as fat substitutes, such as Oatrim and Z-trim.
Carbohydrate-based fat replacers are used in a variety of foods including dairy-type products, frozen desserts, sauces, salad dressings, processed meats, baked goods, spreads, chewing gums and sweets, but they cannot replace fats in frying.
Protein-based fat replacers: These are made from many different types of protein, but soy, egg, milk or whey proteins are common. Microparticulation of protein into tiny, spherical particles that provide a creamy mouthfeel similar to fats helps protein to function as a fat replacer. Blending protein with carbohydrates is another way to create fat replacers. Several studies have shown that combinations of ingredients in fat-replacer formulations create synergy that helps lower fat and helps retain desirable product texture.18,19,20,21,22
Fat replacers from protein and protein blends do provide 4kcal/g, but they may provide only 1-4kcal/g either because they hold water or are used in lesser amounts than fat. For example, 1g Simplesse can replace 3g of fat in cream.
Protein-based fat replacers have been used in fat-free ice cream; low-fat cheese; low-fat baked goods; and reduced-fat versions of butter, sour cream, cheese, yoghurt, salad dressings, margarine, mayonnaise, baked goods, coffee creamers, soups and sauces. Often a combination of these fat replacers can have tremendous potential in the development of fat-modified foods with greater acceptability while lowering the total energy and fat intake.
Fat-based fat replacers: These include common fats that have had chemical alterations of fatty acids so that they deliver less than 0 calories per gram. Some fat-based fat replacers pass through the body partially or totally unabsorbed. Thus they provide less than 9kcal/g or no calories at all. For example, Olestra (Olean) is a sucrose polyester consisting of a mixture of hexa, hepta and octa esters of sucrose, esterified with long-chain fatty acids. Other fat-based fat replacers, such as Salatrim (short- and long-chain triglyceride molecules) and Caprenin, a substitute for cocoa butter in candy bars, are only partially digested and absorbed, and provide 5kcal/g. Some fat replacers, such as Enova oil, are structured diglycerides and are metabolized differently from triglycerides so that some of the energy is lost as heat rather than stored as adipose.
Emulsifiers can be another type of fat-based substances that can be used as fat replacers. They may be used with water to replace all or part of the shortening content in cake mixes, cookies, icings and vegetable and dairy products. They provide the same number of calories as fat, but because less is used in the formulation, the resultant product has less total fat and energy. Mono- and diglycerides are currently used in foods as fat replacers and other substances such as dialkyl dihexadecylmalonate, esterified propoxylated glycerol and trialoxytriartallate are in various stages of development.
Fat replacers and weight loss
Fat replacers can potentially impact overall diet quality and help with weight loss and maintenance. For example, salad dressings and spreads made with fat replacers can help enhance appeal of other nutritious foods such as vegetables and fruit. Thus, fat replacers may help increase the intake of satiety-producing, low-calorie, high-fibre, nutrient-dense foods, while adding few calories. In meat and other food items, fat replacers such as prunes, raisins, cherry paste or wild rice replace some of the fat and increase the antioxidant value of foods while lowering calories. Impact of protein-based: Because these are from milk powder, whey, soy or legumes, they not only have potential to lower calories, but also can increase the protein in the diet or offer some nutritional advantages of the individual protein. Some preliminary data indicate the protein may have an impact on satiety and food consumption in the short term.23,24 Furthermore, protein-based fat replacers have the potential to increase the protein in the diet, and a high protein-to-carbohydrate ratio has been associated in studies with greater weight loss than diets with a lower ratio.25 Dairy-based proteins may add calcium, which has been shown in some studies to be related to weight loss.26 Thus protein-based fat replacers might offer two benefits to the calorie-conscious eater.
Impact of fibre-based: These may offer calorie savings while increasing fibre in the diet.27 Some types of fibre have been shown to regulate food intake, and to aid in both preventing weight gain and helping with weight maintenance.28,29,30,31
One study with male diabetics shows the utility of a fibre-based fat replacer in dealing with obesity and complications associated with it. In this study, those who chose diets rich in fibre-based fat replacers along with sugar replacers and other lifestyle changes reduced body weight and body mass index more than those eating the standard treatment plan. In addition, there were greater decreases in HbA1C (the best measure of glucose because it will be high only if glucose has been elevated for a sustained period of time), and increases in HDL cholesterol.32
In like manner, inclusion of foods made with fat replacers such as Mimex or Oatrim (a powdered soluble oat fibre containing beta-glucans) has been observed to not only lower blood lipid and systolic blood pressure, and improve glucose tolerance and antioxidant status, but it also lowers body weight.33,34,35 Researchers noted that those in the Harvard Nurses' Health Study cohort who had the highest fibre intakes were least likely to gain weight.
Impact of fat-based: These have also been associated with caloric dilution,36 decreased caloric intake and changes in appetite.37 In a study with otherwise healthy and overweight subjects eating foods prepared with fat emulsion of palm oil and oat oil (Olibra, now branded Fabuless by DSM) as a fat replacer, there was decreased total energy intake for up to 36 hours post-consumption. Use of Olibra as a fat substitute in yoghurt significantly reduced the energy and macronutrient intakes relative to use of milk fat.38,39,40
Impact of fat replacers: Use of fat replacers in foods such as mayonnaise, hot dogs and chips has been shown to decrease the energy and fat in products by as much as 50 per cent. In a study where subjects were offered either full-fat or fat-free Olestra-containing chips, total fat intake was reduced from 32-43 per cent in regular chips to 27-30 per cent with Olestra chips.41
Researchers noted that providing free access to reduced-fat products resulted in a reduction in energy intake and percentage energy from fat, while it was associated with an increase in percentage energy from carbohydrate, especially among individuals classified as high-fat consumers.42 Body weight remained stable in the reduced-fat group while it increased significantly by about 1kg in the full-fat group. In addition, cardiovascular disease risk factors such as blood lipids, and hemostatic factors were lower in the reduced-fat group compared to the full-fat group.
In other studies, researchers showed that the selection of low-fat grain mixtures, cakes, cookies and pies not only lowered fat and saturated fat, but resulted in a less energy-dense diet.43,44 The individuals consuming lower-fat foods were more likely to meet nutrient requirements than those consuming higher-fat foods even though they were eating 400-500kcal less.44
Thus, one strategy for combating the obesity epidemic may involve the switch from consumption of full-fat products to lower-calorie, reduced-fat alternatives. An estimated 30 per cent reduction in fat calories and a total calorie reduction of 800kcal can be achieved per week if fat-free products from food categories such as cheese, sour cream, frozen desserts, commercial sweets and baked goods were substituted for their regular versions.45
On the other hand, foods prepared with fat replacers that neither lower calories nor encourage the consumption of foods that are central to the dietary recommendations may do little to improve the quality of the diet. Excessive consumption of brownies, cookies, snack cakes and chips and other such foods made with fat replacers may do little to help in the battle against obesity. This may be especially problematic if the consumer erroneously believes that fat free means calorie free and takes this as a license to consume unlimited amounts.
Julie M Jones is professor in the department of nutrition and food science at College of St Catherine, Minnesota. Satya S Jonnalagadda, PhD, is senior medical affairs specialist at Novartis Medical Nutrition, Minnesota. Respond: firstname.lastname@example.org
1. WHO World Health Organization Consultation on Obesity. Obesity: preventing and managing the global epidemic. World Health Organization, Geneva. 1998.
2. Centers for Disease Control and Prevention: Monitoring the nation's health. Dietary intake of macronutrients, micronutrients, and other dietary constituents: United States: 1988-94. Vital and Health Statistic 2002;11:9-85.
3. Nielsen SJ, et al. Trends in energy intake in US between 1977 and 1996: similar shifts seen across age groups. Obes Res 2002;10:370-8.
4. Swinburn B, Egger G. Preventive strategies against weight gain and obesity. Obesity Rev 2002;3:289-301.
5. Rolls BJ, et al. Portion size of food affects energy intake in normal-weight and overweight men and women. Am J Clin Nutr 2002;76:1207-13.
6. Nielsen SJ, Popkin BM. Patterns and trends in food portion sizes, 1977-1998. JAMA 2003;289:450-3.
7. Young LR, Nestle M. Expanding portion sizes in the US marketplace: implications for nutrition counseling. J Am Diet Assoc 2003;103:23104.
8. Smiciklas-Wright H, et al. Foods commonly eaten in the United States, 1989-91 and 1994-96: are portion sizes changing? J Am Diet Assoc 2003;103:41-7.
9. Kral TV, Roe LS, Rolls BJ. Combined effects of energy density and portion size on energy intake in women. Am J Clin Nutr 2004;79:962-8.
10. Kral TV, et al. Combined effects of energy density and portion size on energy intake in women. Am J Clin Nutr 2004;79:962-8.
11. Devitt AA, Mattes RD. Effects of food unit size and energy density on intake in humans. Appetite 2004;42:213-20.
12. De Castro JM. Dietary energy density is associated with increased intake in free-living humans. J Nutr 2004;134:335-41.
13. Bell EA, Rolls BJ. Energy density of foods affects energy intake across multiple levels of fat content in lean and obese women. Am J Clin Nutr 2001;73:1010-18.
14. Kral TV, et al. Does nutrition information about the energy density of meals affect food intake in normal-weight women? Appetite 2002;39:137-45.
15. Astrup A, et al. The role of low-fat diets in body weight control: a meta-analysis of ad libitum dietary intervention studies. Intl J Obes Relat Metab Disord 2000;24:1545-52.
16. Schwenk NE, Gurhrie JF. Trends in marketing and usage of fat-modified foods: implications for dietary status and nutrition promotion. Fam Eco Nutr Rev 1997;10:16-32.
17. Calorie Control Council. Fat replacers: Food ingredients for healthy eating. www.caloriecontrol.org/fatreprint/html. Accessed 2004 May 6.
18. Conforti FD, Archila L. Evaluation of a maltodextrin gel as a partial replacement for fat in a high-ratio white layer cake. Intl J Consumer Sci 2001;25:238-45.
19. Conforti FD, et al. The synergistic effects of maltodextrin and high fructose corn sweetener 09 in a fat-reduced muffin. Intl J Consumer Sci 2001;25:3-8.
20. Ordonez M, et al. The relationship between the composition and texture of conventional and low-fat frankfurters. Intl J Fd Sci Tech 2001;36:749-58.
21. Ruthig DJ, et al. Health benefits of dietary fat reduction by a novel fat replacer: Mimex. Intl J Fd Sci Nutr 2001;52:61-9.
22. El-Nager G, et al. Rheological quality and stability of yog-ice cream with added inulin. Intl J Dairy Tech 2002;55:89-93.
23. Anderson GH, Moore SE. Dietary proteins in the regulation of food intake and body weight in humans. J Nutr 2004;134:974S-979S.
24. Layman DK, Baum JJ. Dietary protein impact on glycemic control during weight loss. J Nutr 2004;34:968S-973S.
25. Layman DK. Dietary protein and weight. IFT 2004. Annual meeting Las Vegas.
26. Zemel M. Calcium and weight. IFT Annual Meeting, Las Vegas. 2004, July.
27. Inglett G. Development of beta-glucan compositions and their health benefits, annual meeting of the Institute of Food Technologiests June 19, 2002. www.ars.usda.gov/research/publications/publications/htm. Accessed 2004, June 14.
28. Toeller M, et al. Nutrient intakes as predictors of body weight in European people with type 1 diabetes. Int J Obes Relat Metab Disord 2001;25:1815-21.
29. Howarth N, et al. Dietary fiber and weight regulation. Nutr Rev 2001;59:129-39.
30. Archer BJ, et al. Effect of fat replacement by inulin of lupin-kernel fibre on sausage patty acceptability, post-meal perceptions of satiety and food intake in men. Br J Nutr 2004;91:591-9.
31. Laitinen J, et al. Predictors of abdominal obesity among 31-yold men and women born in Northern Finland in 1966. Eur J Clin Nutr 2004;58:180-90.
32. Reyna NY, et al. Sweeteners and beta-glucans improve metabolic and anthropometrics variables in well controlled type 2 diabetes patients. Am J Ther 2003;10:438-43.
33. Inglett G. www.ars.usda.gov/research/publications/publications/htm. Accessed 2004, June 14.
34. Lairon D, et al. French supplementation en vitamins et mineraux antioxidants adult cohort, dietary fibre intake and clinical indices in the French Supplementation en Vitemines et Mineraux AntioXydants adult cohort. Proc Nutr Soc 2003;6:11-15.
35. Liu S, et al. Relation between changes in intakes of dietary fiber and grain products and changes in weight and development of obesity among middle-aged women. Am J Clin Nutr 2003;78:920-7.
36. Glueck CJ, et al. Sucrose polyester and covert caloric dilution. Am J Clin Nutr 1982;35:1352-9.
37. Burley VJ, et al. Effect on appetite of replacing natural fat with sucrose polyester in meals or snacks across one whole day. In: Ditschuneit H, et al (eds) Obesity in Europe. Libbey, Londong 1994;227-33.
38. Burns AA, et al. Short-term effects of yoghurt containing a novel fat emulsion on energy and macronutrient intakes in non-obese subjects. Int J Obes Relat Metab Disord 2000;24:1419-25.
39. Burns AA, et al. The effects of yohgurt containing a novel fat emulsion on energy and macronutrient intake in lean, overweight and obese subjects. Intl J Obes Relat Metab Disod 2001;25:1487-96.
40. Burns AA, et al. Dose-response effects of a novel fat emulsion (Olibra) on energy and macronutrient intakes up to 36h post-consumption. Eur J Clin Nutr 2002;56:368-77.
41. Miller DL, et al. Effects of fat-free potato chips with and without nutrition labels on fat and energy intakes. Am J Clin Nutr 1998;68(2):282-90.
42. Weststrate JA, et al. A comparison of the effect of free access for educed fat products or their full fat equivalents on food intake, body weight, blood lipids and fat-soluble antioxidants levels and haemostatis variables. Eur J Clin Nutr 1998;52:389-95.
43. Kennedy ET, et al. Dietary-fat intake in the US population. J Am Coll Nutr 1999;19:207-12.
44. Kennedy E, et al. Assessment of the effect of fat-modified foods on diet quality in adults, 19-50 years, using data from the Continuing Survey of Food Intake by Individuals. J Am Diet Assoc 2001;101:455-60.
45. Lyle B, et al. Assessing the potential dietary impacts of replacing dietary fat with other macronutrients. Nutr 1992;122:211-6.
46. Sigman-Grant M, et al. Selected lower-fat foods positively impact nutrient quality in diets of free-living Americans. J Am Diet Assoc 2003;103:570-6.
47. Swanson RB, et al. Acceptability of reduced-fat brownies by school-aged children. A Am Diet Assoc 2002;102:856-9.
48. Eldridge AL, et al. A role for olestra in body weight management. Obesity Rev 2002;3:17-25.