National Heart Foundation of Australia position statement on dietary fat and overweight/obesity.Key words: dietary fat, overweight, obesity, energy balance, energy density The National Heart Foundation of Australia's (NHFA NHFA National Home Furnishings Association NHFA National Hispanic Foundation for the Arts NHFA New Hampshire Flying Association ) review of the relationship between dietary fat and cardiovascular disease Cardiovascular disease Disease that affects the heart and blood vessels. Mentioned in: Lipoproteins Test cardiovascular disease (CVD CVD Cardiovascular disease, see there ) while finding good evidence of a link between the amount of saturated fat saturated fat, any solid fat that is an ester of glycerol and a saturated fatty acid. The molecules of a saturated fat have only single bonds between carbon atoms; if double bonds are present in the fatty acid portion of the molecule, the fat is said to be in the diet and CVD risk, found little evidence demonstrating that coronary events or death are linked to the amount of total fat in the diet (1). However, it has been suggested that dietary fat intake could increase the risk of CVD indirectly by increasing the risk of overweight and obesity, an independent risk factor for morbidity and mortality Morbidity and Mortality can refer to:
coronary heart disease or ischemic heart disease Progressive reduction of blood supply to the heart muscle due to narrowing or blocking of a coronary artery (see atherosclerosis). (CHD CHD coronary heart disease. ChD abbr. Latin Chirurgiae Doctor (Doctor of Surgery) CHD, n.pr See disease, coronary heart. CHD canine hip dysplasia. ). A review of the relationship between dietary fat and overweight/obesity was therefore conducted to determine whether recommendations on total fat intake were required for the prevention of cardiovascular disease. Objectives The objectives of the review of the relationship between dietary fat and overweight/obesity were to: * Determine whether dietary fat, independent of energy intake, is a risk factor for the development and progression of overweight and obesity. * Assess the effectiveness of fat reduction strategies relative to other dietary strategies for achieving weight loss in overweight and obese individuals and weight maintenance in normal weight, overweight and obese individuals. The following summary is based on the evidence contained within the Heart Foundation's background review paper completed in February 2003 (2). Summary of conclusions Dietary fat is not an independent risk factor for the development and progression of overweight and obesity (moderate evidence). Dietary fat may increase the risk of overweight and obesity indirectly by increasing the energy density of the diet, hence facilitating excess energy intake. The association between dietary fat and obesity reported in cohort studies, conducted in different population groups, was inconsistent (3-10). Inconsistency in the findings can be partly explained by measurement bias, in particular underreporting of dietary fat intake and confounding confounding when the effects of two, or more, processes on results cannot be separated, the results are said to be confounded, a cause of bias in disease studies. confounding factor from physical activity. The lack of variation in dietary fat intakes in the study populations and the large within-person variation in dietary intake make it difficult to find an association between dietary fat intake and weight gain in cohort studies (11). Overall, the effect of dietary fat was small compared to other risk factors for overweight and obesity, such as physical activity level. No study reported a dose response relationship between dietary fat intake and weight gain. Criteria The following criteria were used to assess the evidence in this review:
Good evidence
Level of evidence Consistency across several
study designs, including
long term intervention
studies
Quality of the evidence Measurement bias
adequately minimized
Size of the effect Statistically significant
Mechanism Metabolic studies in humans
Level of evidence Inconsistency across study
designs; use of surrogate
measures; limited number and
type of studies
Quality of the evidence Limited in quality
Size of the effect Effect possibly due to
measurement bias
Mechanism Metabolic studies in humans
Little evidence
Level of the evidence Inconsistency across study
designs; limited number and type
Of studies
Quality of the evidence Limited in quality
Size of the effect Effect possibly due to
measurement bias
Mechanism Lack of metabolic studies in
humans
It is unlikely that the metabolic effect of dietary fat on energy expenditure and energy storage increases the risk of weight gain. Several controlled trials in normal weight women and men suggest that high fat diets do not result in excess energy intake when confounding factors, such as energy density and palatability, are held constant (12-14). Several controlled trials in both obese and lean individuals have shown that energy intake is dependent on the energy density of the diet, not the fat content. Energy intake was higher with high energy dense diets (above 6 kJ/g) than low energy dense diets (to less than 4 kJ/g)(15-18). Since energy density is mainly determined by the water, fat and fibre content of foods, high fat diets may lead to excess energy intake and hence contribute to weight gain. However, other factors such as palatability, the physical form of food, the amount (portion size) and volume of food consumed as well as behavioural and genetic factors, may also influence energy intake. Energy balance is the major determinant of weight loss. Dietary fat reduction is a simplistic sim·plism n. The tendency to oversimplify an issue or a problem by ignoring complexities or complications. [French simplisme, from simple, simple, from Old French; see simple behavioural strategy to facilitate energy restriction. However, without energy restriction, fat reduction alone is not effective for achieving weight loss in overweight and obese individuals (moderate evidence). Randomised Adj. 1. randomised - set up or distributed in a deliberately random way randomized irregular - contrary to rule or accepted order or general practice; "irregular hiring practices" controlled trials in obese individuals reported no significant differences in short-term weight loss between energy-restricted diets (1000 to 1200 kcal) varying in fat content from 15% to 75% energy from fat (%E fat) (19-21). An interim systematic review concluded that low-energy, low-fat diets are not more efficacious than low-energy diets, which are not low in fat, in terms of weight loss in overweight or obese individuals (22). Reducing dietary fat intake to 25%E (30 to 35 g/day) appears to be as effective as restricting energy intake to 5040 kJ/day for achieving short-term (six months) weight loss in obese women (23). However, a randomised controlled trial suggests that short-term weight loss achieved with both low fat ad libitum ad libitum without restraint. ad libitum feeding food available at all times with the quantity and frequency of consumption being the free choice of the animal. dietary interventions (dietary fat reduced to 25%E fat or 30 to 35 g fat/day) and energy restricted diets (around 5040 kJ/day) in free-living obese individuals is not maintained in the long term, after controlling for confounding factors (24). Other factors, such as physical activity, social support and preference for the dietary regime have been shown to also influence weight loss. Controlled trials suggest that low-fat ad libitum dietary interventions may reduce energy intake leading to short-term weight loss in overweight individuals (25,26). A meta-analysis of low-fat ad libitum dietary intervention studies intervention studies, n.pl the epidemiologic investigations designed to test a hypothesized cause and effect relation by modifying the supposed causal factor(s) in the study population. , in which weight loss was not the primary aim of the majority of these studies, reported a weighted difference in weight loss between intervention and control groups of 2.55 kg (95% CI: 1.5 to 3.5 kg; P < 0.0001) (23). However, few studies separated the effect of dietary fat from other confounding factors such as physical activity, other dietary factors and behavioural influences. Randomised controlled trials suggest that there is a wide variation in short-term weight loss achieved in obese individuals on low-fat (30%E fat) ad libitum diets (27,28). Differences in the protein content, and to a lesser extent, the type of carbohydrate in the low-fat ad libitum diet resulted in significant (3.7 kg 95% CI: 1.3 to 6.2 kg; P = 0.0002) and non-significant differences in weight loss, respectively. A randomised crossover study A crossover trial also referred to as a crossover study is one where patients are given all of the medications to be studied, or one medication and a placebo in random order. These studies are generally done on patients with chronic diseases to control their symptoms. found no significant difference in short-term weight loss in overweight women on a low-fat diet (22%E fat) compared to those on a high monounsaturated fat monounsaturated fat A saturated fatty acid–ie, an alkyl chain fatty acid with one ethylenic–double bond between the carbons in the fatty acid chain. See Fatty acid, Saturated fatty acid; Cf Polyunsaturated fatty acid, Unsaturated fatty acid. diet (36%E fat) (29). It may therefore be possible that dietary fat intakes of up to 35%E fat can be consumed as long as the overall diet is low in energy density (i.e. less than 5 kJ/g). Dietary fat reduction alone may be effective for preventing weight gain in normal weight, overweight and obese individuals (little evidence). Few controlled trials have measured the independent effect of dietary fat reduction on weight maintenance in normal, overweight and obese individuals. A randomised controlled trial suggests energy intake is significantly decreased in normal weight men (P < 0.01) and women (P < 0.0001) when dietary fat intake is reduced from 35%E fat to 33%E fat, whereas energy intake is significantly increased only in women (P < 0.01) when dietary fat intake is increased from 35%E fat to 41.2%E fat (30). Body weight was significantly increased on the high fat diet (40%E or 122 g/day) in both men (P < 0.001) and women (P < 0.01) but remained unchanged on the low fat diet (33%E fat or 89 g fat/day). Eating behaviour may explain differences in the effect of dietary fat reduction on energy intake and consequent weight change in normal weight individuals (31). The long-term effect of dietary fat reduction strategies on weight maintenance in normal weight and overweight individuals has not been demonstrated. It is recommended that public health nutrition strategies for the prevention of cardiovascular disease emphasise reducing saturated fatty acid saturated fatty acid n. A fatty acid, such as stearic acid, whose carbon chain contains no unsaturated linkages between carbon atoms and hence cannot incorporate any more hydrogen atoms. intake. Current levels of dietary fat intake in Australia are around 32%E fat (32). Average intakes of saturated and polyunsaturated fatty acids Noun 1. polyunsaturated fatty acid - an unsaturated fatty acid whose carbon chain has more than one double or triple valence bond per molecule; found chiefly in fish and corn and soybean oil and safflower oil (12.7% and 4.9%E, respectively) are not consistent with the NHFA's policy on dietary fat ([less than or equal to] 8%E saturated and 8 to 10% polyunsaturated polyunsaturated /poly·un·sat·u·rat·ed/ (-un-sach´er-at-ed) denoting a chemical compound, particularly a fatty acid, having two or more double or triple bonds in its hydrocarbon chain. )(1,33). Intake of total dietary fat and polyunsaturated fatty acids in the Australian diet has decreased since 1983, while intake of total energy and saturated fatty acids
Most commonly occurring saturated fatty acids are:
The evidence reviewed suggests that dietary fat intake of 30 to 35%E does not seem to be associated with excess energy intake. Since dietary fat restriction may help to facilitate energy restriction, public health recommendations should ensure that dietary fat intake remains at less than 35% energy from fat. The emphasis of food-based recommendations for the prevention of CHD, developed by the NHFA, is on reducing intake of foods high in saturated fatty acids, such as full fat dairy products dairy products dairy npl → produits laitier dairy products dairy npl → Milchprodukte pl, Molkereiprodukte pl , takeaway meals, pastries, snacks and cakes. Reducing intake of saturated fatty acids is likely to also reduce total dietary fat intake. Furthermore, since many foods high in saturated fatty acids are also high in energy density, restricting their intake also facilitates a reduction in energy intake. Further research required Energy density may be a major determinant of energy intake although protein intake may act independently of this. Further research is required to determine the relative effectiveness of manipulating the dietary macronutrient macronutrient /mac·ro·nu·tri·ent/ (-noo´tre-ent) an essential nutrient required in relatively large amounts, such as carbohydrates, fats, proteins, or water; sometimes certain minerals are included, such as calcium, chloride, or sodium. , fibre and water content of foods on reducing the energy density of the overall diet. Long-term studies are required to determine whether strategies for reducing the energy density of the diet are useful for achieving weight loss in overweight and obese individuals and weight maintenance in normal weight as well as overweight and obese individuals. Other dietary and non-dietary factors are also implicated im·pli·cate tr.v. im·pli·cat·ed, im·pli·cat·ing, im·pli·cates 1. To involve or connect intimately or incriminatingly: evidence that implicates others in the plot. 2. in the development and progression of overweight and obesity. Clearly physical activity plays an important role in regulating body weight. Further research is required to determine the combined effect of dietary and physical activity strategies in weight management. References (1.) National Heart Foundation of Australia The National Heart Foundation of Australia (NHF) or Heart Foundation [1] is a non-profit organization with the stated mission "to improve the cardiac health of Australians". It was formed in 1959 by a group of cardiac physicians. . A review of the relationship between dietary fat and cardiovascular disease. Aust J Nutr Diet 1999;56(4):Suppl. (2.) National Heart Foundation of Australia. A review of the relationship between dietary fat and overweight/obesity. 2003: NHFA Review. http://www.heartfoundation.com.au/index.cfm?page=41 (3.) Colditz GA, Willett WC, Stampfer MJ, London SJ, Segal MR, Speizer FE. Patterns of weight change and their relation to diet in a cohort of healthy women. Am J Clin Nutr 1990;51:1100-5. (4.) Rissanen AM, Heliovaara M, Knekt P, Reunanen A, Aromaa A. Determinants of weight gain and overweight in adult Finns. Eur J Clin Nutr 1991;54:419-30. (5.) Klesges RC, Klesges LM, Haddock CK, Eck LH. A longitudinal analysis of the impact of dietary intake and physical activity on weight change in adults. Am J Clin Nutr 1992;55:818-22. (6.) Kant AK, Graubard BI, Schatzkin A, Ballard-Barbash R. Proportion of energy intake from fat and subsequent weight change in the NHANES NHANES National Health and Nutrition Examination Survey (US CDC) I Epidemiologic Follow-up Study. Am J Clin Nutr 1995;61:11-7. (7.) Heitmann BL, Lissner L, Sorensen TIA (1) (Telecommunications Industry Association, Arlington, VA, www.tiaonline.org) A membership organization founded in 1988 that sets telecommunications standards worldwide. It was originally an EIA working group that was spun off and merged with the U.S. , Bengtsson C. Dietary fat intake and weight gain in women genetically predisposed pre·dis·pose v. pre·dis·posed, pre·dis·pos·ing, pre·dis·pos·es v.tr. 1. a. To make (someone) inclined to something in advance: for obesity. Am J Clin Nutr 1995;61:1213-7. (8.) Jorgensen LM, Sorensen TI, Schroll M, Larsen S. Influence of dietary factors on weight change assessed by multivariate graphical models, Int J Obes Relat Metab Disord 1995;12:909-15. (9.) Lissner L, Heitmann BL, Bengtsson C. Low-fat diets may prevent weight gain in sedentary women: prospective observations from the population study of women in Gothenburg, Sweden. Obes Res 1997:5:43-8. (10.) Paeratakul S, Popkin BM, Keyou G, Adair LS, Stevens J. Changes in diet and physical activity affect the body mass index of Chinese adults. Int J Obes Relat Metab Disord 1998;22:424-31. (11.) Sempos CT, Liu K, Ernst ND. Food and nutrient exposures: what to consider when evaluating epidemiologic evidence. Am J Clin Nutr 1999;69:1330S-8S. (12.) van Stratum stratum /stra·tum/ (strat´um) (stra´tum) pl. stra´ta [L.] a layer or lamina. stratum basa´le P, Lussenburg RN, van Wezel LA, Vergroesen AJ, Cremer HD. The effect of dietary carbohydrate:fat ratio on energy intake by adult women. Am J Clin Nutr 1978;31:206-12. (13.) Stubbs RJ, Harbron CG. Prentice AM. Covert manipulation of the dietary fat to carbohydrate ratio of isoenergetically dense diets: effect on food intake in feeding men ad libitum. Int J Obes 1996;20:651-60. (14.) Salzman E, Dallal GE, Roberts SB. Effect of high-fat and low-fat diets on voluntary energy intake and substrate oxidation: studies in identical twins identical twins pl.n. Twins derived from the same fertilized ovum that at an early stage of development becomes separated into independently growing cell aggregations, giving rise to two individuals of the same sex, identical genetic makeup, and consuming diets matched for energy density, fiber, and palatability. Am J Clin Nutr 1997;66:1332-9. (15.) Rolls BJ, Bell EA. Energy density but not fat content of foods affected energy intake in lean and obese women. Am J Clin Nutr 1999;69:863-71. (16.) 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. (17.) Bell EA, Castellanos VH, Pelkman CL, Thorwart ML, Rolls BJ. Energy density of foods affects energy intake in normal-weight women. Am J Clin Nutr 1998;67:412-20. (18.) Stubbs RJ, Johnstone AM, O'Reilly LM, Barton K, Reid C. The effect of covertly manipulating the energy density of mixed diets on ad libitum food intake in 'pseudo free-living' humans. Int J of Obesity 1998;22:980-7. (19.) Powell JJ, Tucker L, Fisher AG, Wilcox K. The effects of different percentages of dietary fat intake, exercise, and calorie restriction
Calorie restriction or Caloric restriction (CR) is the practice of limiting dietary energy intake in the hope that it will improve health and retard aging. on body composition and body weight in obese females. Am J Health Promot 1994;8:442-8. (20.) Lean ME, Han TS, Richmond PR, Avenell A. Weight loss with high and low carbohydrate 1200 kcal diets in free living women. Eur J Clin Nutr 1997;51:243-8. (21.) Golay A, Allaz AF, Morel morel Any of various species of edible mushrooms in the genera Morchella and Verpa. Morels have a convoluted or pitted head, or cap, vary in shape, and occur in diverse habitats. The edible M. Y, de Tonnac N, Tankova S, Reaven G. Similar weight loss with low- or high-carbohydrate diets. Am J Clin Nutr 1996;63:174-8. (22.) Summerbell CD, Jones LV, Glasziou P. The long-term effect of advice on low-fat diets in terms of weight loss: an interim meta-analysis. J Human Nutr Diet 1998;11:209-17. (23.) Astrup A, Ryan L, Grunwald GK, Storgaard M, Saris SARIS Search and Rescue Information System SARIS Scattering And Recoiling Imaging Spectrometry SARIS Savannah River Simulator SARIS Spatial/Spectral Airborne Radiometric Imaging Spectrometer (Spectral imaging system used at Eglin AFB) W, Melanson E, et al. The role of dietary fat in body fatness: evidence from a preliminary meta-analysis of ad libitum low-fat dietary intervention studies. Br J Nutr 2000;83,Suppl 1:25S-32SS. (24.) Jeffery RW, Hellerstedt WL, French SA, Baxter JE. A randomized ran·dom·ize tr.v. ran·dom·ized, ran·dom·iz·ing, ran·dom·iz·es To make random in arrangement, especially in order to control the variables in an experiment. trial of counseling for fat restriction versus calorie restriction in the treatment of obesity. Int J Obes Relat Metab Disord 1995;19:132-7. (25.) Swinburn BA, Woollard GA, Chang EC, Wilson MR. Effects of reduced-fat diets consumed ad libitum on intake of nutrients, particularly antioxidant vitamins. J Am Diet Assoc 1999;99:1400-5. (26.) Siggaard R, Raben A, Astrup A. Weight loss during 12 weeks' ad libitum carbohydrate-rich diet in overweight and normal-weight subjects at a Danish work site. Obes Res 1996;4:347-56. (27.) Skov AR, Toubro S, Ronn B, Holm holm n. Chiefly British An island in a river. [Middle English, from Old Norse h L, Astrup A. Randomized trial on protein vs carbohydrate in ad libitum fat reduced diet for the treatment of obesity. Int J Obes Relat Metab Disord 1999;23:528-36. (28.) Saris WHM WHM Web Host Manager WHM White Mage (Final Fantasy, gaming) WHM White Marlin (FAO fish species code) WHM Wireless Host Module WHM Workshop on Human Motion (IEEE Workshop) , Astrup A, Prentice AM, Zunft, HJF HJF Henry Jackson Foundation (Rockville, MD) , Formiguera X, Verboeker-van de Venne WP, et al. Randomized controlled trial A randomized controlled trial (RCT) is a scientific procedure most commonly used in testing medicines or medical procedures. RCTs are considered the most reliable form of scientific evidence because it eliminates all forms of spurious causality. of changes in dietary carbohydrate/fat ratio and simple vs complex carbohydrates complex carbohydrates, n.pl polysaccharides; nutritional compounds composed of multiple monosaccharide (simple sugar) building blocks. Complex carbohydrates include starches, glycogen, and cellulose. on body weight and blood lipids: the CARMEN study. Int J Obes 2000;24:1310-18. (29.) Walker KZ, O'Dea K, Nicholson GC. Dietary composition affects regional body fat distribution and levels of dehydroepiandrosterone sulphate sulphate: see sulfate. (DHEAS DHEAS Dehydroepiandrosterone Sulfate ) in post-menopausal women with Type 2 diabetes type 2 diabetes n. See diabetes mellitus. . Eur J Clin Nutr 1999;53:700-5. (30.) Westerterp KR, Verboeket-van de Venne WP, Westerterp-Plantenga MS, Velthuis-te Wierik EJ, de Graaf C, Weststrate JA. Dietary fat and body fat: an intervention study. Int J Obes Relat Metab Disord 1996;20:1022-6. (31.) Westerterp-Plantenga MS, Wijckmans-Duijsens NE, Verboeket-van de Venne WP, de Graaf K, van het Hof KH, Weststrate JA. Energy intake and body weight effects of six months reduced or full fat diets, as a function of dietary restraint. Int J Obes Relat Metab Disord 1998;22:14-22. (32.) Australian Bureau of Statistics The Australian Bureau of Statistics (ABS) is the Australian government agency that collects and publishes statistical information about Australia and its people. Population and Housing The agency undertakes the Australian Census of Population and Housing. and Commonwealth Department of Health and Family Services. National Nutrition Survey: Selected Highlights Australia. Catalogue No 4802.0. Canberra: Australian Bureau of Statistics; 1997. (33.) Australian Bureau of Statistics and Commonwealth Department of Health and Family Services. Nutrient intakes and physical measurements. Catalogue No 4805.0. Canberra: Australian Bureau of Statistics; 1998. (34.) Cook T, Rutishauser I, Allsopp R. The Bridging Study--comparing results from the 1983, 1985 and 1995 Australian national nutrition surveys. 2001: The Australian Food and Nutrition Food and Nutrition See also cheese; dining; milk. accubation Rare. the act or habit of reclining at meals. alimentology Medicine. thescience of nutrition. allotriophagy Pathology. Monitoring Unit; http://www.sph.uq.edu.au/nutrition/monitoring/index.htm |
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