Effect of Fructose on Body Weight in Controlled Feeding Trials

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    cvictorg

    cvictorg Active Member

    Effect of Fructose on Body Weight in Controlled Feeding Trials

    Effect of Fructose on Body Weight in Controlled Feeding Trials
    A Systematic Review and Meta-analysis

    John L. Sievenpiper, MD, PhD; Russell J. de Souza, ScD, RD; Arash Mirrahimi, HBSc; Matthew E. Yu, HBSc; Amanda J. Carleton, MSc; Joseph Beyene, PhD; Laura Chiavaroli, MSc; Marco Di Buono, PhD; Alexandra L. Jenkins, PhD, RD; Lawrence A. Leiter, MD; Thomas M.S. Wolever, MD, PhD; Cyril W.C. Kendall, PhD; and David J.A. Jenkins, MD, PhD, DSc

    Abstract

    Background: The contribution of fructose consumption in Western diets to overweight and obesity in populations remains uncertain.

    Purpose: To review the effects of fructose on body weight in controlled feeding trials.

    Data Sources: MEDLINE, EMBASE, CINAHL, and the Cochrane Library (through 18 November 2011).

    Study Selection: At least 3 reviewers identified controlled feeding trials lasting 7 or more days that compared the effect on body weight of free fructose and nonfructose carbohydrate in diets providing similar calories (isocaloric trials) or of diets supplemented with free fructose to provide excess energy and usual or control diets (hypercaloric trials). Trials evaluating high-fructose corn syrup (42% to 55% free fructose) were excluded.

    Data Extraction: The reviewers independently reviewed and extracted relevant data; disagreements were reconciled by consensus. The Heyland Methodological Quality Score was used to assess study quality.

    Data Synthesis: Thirty-one isocaloric trials (637 participants) and 10 hypercaloric trials (119 participants) were included; studies tended to be small (<15 participants), short (<12 weeks), and of low quality. Fructose had no overall effect on body weight in isocaloric trials (mean difference, ?0.14 kg [95% CI, ?0.37 to 0.10 kg] for fructose compared with nonfructose carbohydrate). High doses of fructose in hypercaloric trials (+104 to 250 g/d, +18% to 97% of total daily energy intake) lead to significant increases in weight (mean difference, 0.53 kg [CI, 0.26 to 0.79 kg] with fructose).

    Limitations: Most trials had methodological limitations and were of poor quality. The weight-increasing effect of fructose in hypercaloric trials may have been attributable to excess energy rather than fructose itself.

    Conclusion: Fructose does not seem to cause weight gain when it is substituted for other carbohydrates in diets providing similar calories. Free fructose at high doses that provided excess calories modestly increased body weight, an effect that may be due to the extra calories rather than the fructose.

    Primary Funding Source: Canadian Institutes of Health Research. (ClinicalTrials.gov registration number: NCT01363791)

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    Replies to Effect of Fructose on Body Weight in Controlled Feeding Trials

    Overweight, and metabolic disorders: need for more clinical trials before blaming (or not) fructose

    Luc Tappy
    Department of Physiology, Faculty of Biology and Medicine, University of Lausanne

    This meta-analysis elegantly demonstrates that fructose consumption will not lead to body weight gain unless energy intake is in excess of energy expenditure. It thus demonstrates that there is nothing extraordinary about fructose and that the laws of thermodynamics remain valid even when it is present in our diet. This apparently trivial observation is nonetheless relevant, given recent statements proposing that fructose is a major cause for metabolic disorders, and calling for immediate litigation to limit fructose intake (1). Such statements stand on several reports showing that high fructose intake causes adverse metabolic effects in animal models and in humans (2), on epidemiological studies showing a relationship between the consumption of caloric sweeteners and metabolic diseases (3), and on basic research reports having identified a variety of mechanisms by which fructose can impair insulin's actions (2). Although the meta-analysis by Sievenpiper et al usefully recalls that fructose per se will not increase body weight irrespective of energy balance, there remain other, important issues which need to be addressed before concluding that it is safe: 1) Does dietary fructose impair the control of food intake? If that were the case, a high fructose intake may induce excess energy intake, and hence cause body weight gain. 2) Is body fat preferentially localized in visceral adipose tissue when fructose is consumed in excessive amounts, as recently suggested (4)? This would of course have potential consequences on insulin sensitivity and metabolic control. 3) Does the consumption of fructose with sweetened beverages increase our overall energy intake due to inadequate compensation of liquid calories (5)? 4) Does consumption of fructose cause metabolic disorders irrespective of body weight gain? Hypercaloric, very high fructose diets produce potentially deleterious effects in humans (2). Whether this is also true in the absence of excess energy intake and how this is modulated by other environmental factors (exercise, other nutrients) remains unknown and calls for more clinical studies. There are indeed reasons to be concerned about an excessive intake of fructose, whether from added sugars or High Fructose Corn Syrups. There are more specific concerns regarding consumption of sugar-sweetened beverages, which may not be adequately compensated, and it appears certainly sound to take practical steps to limit their use. There is, however, a need for additional, clinically relevant studies before taking drastic public health actions to specifically target fructose-containing caloric sweeteners.

    References

    1. Lustig RH, Schmidt LA, Brindis CD. Public health: The toxic truth about sugar. Nature. 2012;482(7383):27-9.

    2. Tappy L, Le KA. Metabolic effects of fructose and the worldwide increase in obesity. Physiol Rev. 2010;90(1):23-46.

    3. Malik VS, Hu FB. Sweeteners and Risk of Obesity and Type 2 Diabetes: The Role of Sugar-Sweetened Beverages. Current Diabetes Reports. 2012.

    4. Stanhope KL, Schwarz JM, Keim NL, Griffen SC, Bremer AA, Graham JL, et al. Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. J Clin Invest. 2009.

    5. Pan A, Hu FB. Effects of carbohydrates on satiety: differences between liquid and solid food. Current opinion in Clinical Nutrition and Metabolic Care. 2011;14(4):385-90.

    Conflict of Interest:
    None declared
     

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