Despite many interesting theories on how fructose may or may not be ‘metabolically’ different from sucrose or glucose, whether fructose in and of itself is a major player in these problems remains unresolved (despite vehement and passionate arguments on both sides of the debate).
It is therefore of interest, that an extensive systematic review and meta-analysis of the impact of fructose on body weight in controlled feeding trials by John Sivenpiper and colleagues from across Canada, published last week in the Annals of Internal Medicine, fails to find any significant impact of fructose on body weight other than what can be attributed to its caloric content.
Thus, the researchers performed an electronic literature search to identify 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).
As the researchers were specifically interested in whether or not fructose is the culprit, they excluded studies evaluating high-fructose corn syrup, which only contains about 42% to 55% of free fructose.
Thirty-one isocaloric trials (637 participants) and 10 hypercaloric trials (119 participants) were included in the analyses and the authors noted that studies tended to be small (<15 participants), short (<12 weeks), and of low quality.
Nevertheless, there was no evidence that fructose had any 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).
Only at high doses of fructose (+104 to 250 g/d, +18% to 97% of total daily energy intake) in the hyper caloric trials was there a significant, albeit modest, increases in weight (about 1 pound), which the authors largely attribute to increased caloric intake.
According to the authors:
“…aggregate data analyses of controlled feeding trials do not support a body weight–increasing effect of fructose in isocaloric exchange for other sources of carbohydrate in the diet. However, evidence indicates that added fructose providing excess energy at extreme levels of intake may have a body weight–increasing effect over the short term, although confounding from excess energy cannot be excluded.”
Thus, despite methodological limitations, there is currently no clear evidence that fructose contributes to weight gain other than by simply providing (extra) calories. In other words, were you to replace the calories from fructose by the same amount of calories from other sugars, your weight would be exactly the same.
Not that this means that increased consumption of excess calories as fructose or otherwise may not be part of the obesity problem – it just does not seem that there is anything particularly ‘bad’ about fructose, as far as weight is concerned.
Others have suggested that fructose may have other detrimental properties that could cause metabolic problems like insulin resistance, fatty liver disease, or elevated triglycerides, but human data on this is likewise sparse (and was not topic of this review).
I believe, based on these findings, that eliminating fructose from your diet only to replace it with another sugar is unlikely to make any difference as far as weight management is concerned. At least, there does not appear to be any hard data suggesting that it would.
Sievenpiper JL, de Souza RJ, Mirrahimi A, Yu ME, Carleton AJ, Beyene J, Chiavaroli L, Di Buono M, Jenkins AL, Leiter LA, Wolever TM, Kendall CW, & Jenkins DJ (2012). Effect of Fructose on Body Weight in Controlled Feeding Trials: A Systematic Review and Meta-analysis. Annals of internal medicine, 156 (4), 291-304 PMID: 22351714
Yesterday’s Summit on Healthy Weights brought together a wide range of stakeholders from all sectors to discuss community based responses towards improving health and wellness in Canada’s children and youth.
In the discussion, I was particularly pleased to hear the Honourable Minister Leona Aglukkaq point out the importance of ensuring that community based interventions were culturally appropriate and community driven with a focus on improving health and wellness rather than simply reducing weights.
A particular challenge exists in Canada’s North, where communities are isolated with less availability of affordable healthy foods. Lifestyle transition has significantly reduced hunting and gathering of traditional foods, which provided these populations with nutritious and delicious diet.
As Gita Sharma, Endowed Chair in Aboriginal Health at the University of Alberta, a participant at this meeting pointed out,
“It is essential to work with Aboriginal communities to have community driven multi-institutional nutrition and physical activity intervention programs, that are evidence-based and evaluated. These programs must also provide training and capacity building for employment at the local level, so communities can implement these programs and ensure sustainability.”
Gita Sharma emphasized the benefits of partnerships with the food retail based companies, as people make decisions about food choices at the point of purchase, making this the natural target for community based nutrition interventions. In addition, findings from such research must be distributed to the communities, stakeholders, and to the endusers to guide policy.
Given the importance of culturally appropriate community and population-specific interventions, the Canadian Obesity Network will dedicate a full day to this issue at the 3rd National Obesity Summit, in Vancouver next year.
According to the press release,
“The Summit brings together for the first time a diverse cross-section of government and non-government partners to plan collaborative action for reversing the rising trend of childhood overweight and obesity.”
While this may well be, regular readers of these pages will note that the focus on childhood obesity in isolation is neither likely to be effective nor fiscally feasible. Indeed, there is much evidence to suggest that a) the ‘root cause’ of obesity actually lies in fundamental and deep-rooted societal changes that may take decades to reverse (if at all) and b) will also need to ultimately address obesity in the parents, who themselves more often than not, struggle with excess weight.
Thus, I see no reason to believe that a focus on children, without also addressing the very issues that lead to obesity in the parents, is likely to be effective. Indeed, for many overweight and obese children (and their parents) it is no longer a matter of prevention – it is high time for treatment.
Indeed, emerging evidence from animal and human studies on epigenetic programming, suggests that any efforts to ‘prevent’ childhood obesity once the child is born, may be described as ‘secondary’ prevention at best.
In addition, efforts that essentially aim to prescribe a simplistic “eat-less-move-more” (ELLM) approach to the population, is likely to prove as ineffective, as such approaches have proven in individuals.
Nevertheless, the fact that the Canadian government is now recognizing the importance of obesity and is perhaps ready to rally all relevant government and non-governmental stakeholders to address this issue, is encouraging.
I certainly know that Canada’s only national obesity organization, the Canadian Obesity Network, with its over 7000 obesity researcher and health professional members, stands ready to lead the way.
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Have a great Sunday! (or what is left of it)
Continuing my series of past papers on obesity, here is a rather technical paper that we published in METABOLISM back in 2000.
This work was again led by my student Iris Kunz and was done in collaboration with Susanne Klaus at the German Institute of Human Nutrition, Potsdam-Rehbrücke.
The aim of this work was to carefully examine the time course of energy expenditure after a meal, which we know can vary widely with regard to the slope of onset, amplitude, and duration of the thermic effect.
In this paper, we explore the relationship between the thermic effect of food (TEF), as characterized by kinetic analysis of postprandial energy expenditure, body composition, and variables related to the metabolic syndrome including central obesity, hypertension, and glucose tolerance.
A total of 181 men and women (body mass index [BMI] range, 19.4 to 52.2 kg/m2) were characterized for body composition, blood pressure, oral glucose tolerance, and energy expenditure after a test meal.
Energy expenditure, as measured by indirect calorimetry, was analyzed over a 6-hour period by 3-parameter curve fitting using equations derived from kinetics describing a biphasic reaction involving 2 consecutive first-order reactions (A–>B–>C). The equations we came up with, performed with a reasonable fit in 91.7% of the subjects, indicating that these equations represent a good model for describing the thermic response to a meal.
Apart from total thermic effect of food (TEFk), the curve also provided an estimate of time of peak (Tp) and amplitude of peak (Ap) for each subject.
As reported by other investigators, we found that energy expenditure does not return to baseline for as long as 5 to 6 hours, particularly with a high-protein meal as used in our study, which is known to elicit a longer and greater thermogenic response than a high- carbohydrate or high-fat meal. (In lay terms this simply means that you burn more of the calories contained in a protein meal simply by the effort it takes to digest and process the protein – this is why you often breakout into a sweat when eating a high-protein meal – think lobster dinner).
Multiple stepwise regression analysis with TEFk, Ap, and Tp as dependent variables showed significant effects of sex, age, body weight, body fat, beta-blockade, and body composition on TEF curve parameters.
Cluster analysis based on Tp shown 2 distinct clusters with significant differences in age and body fat mass.
“Thus, while Ap was higher in men than in women, Tp was delayed in older individuals and in patients on B-blockers and was positively related to relative fat mass. These findings are supported by the results of the cluster analysis, which showed 2 distinct patterns: CLU1, with a higher Ap and shorter Tp, and CLU2, with a lower Ap and extended Tp. Patients in CLU1 were younger, had a higher FFM, and were less likely to be on B-blockers than patients in CLU2. In contrast, BMI, body weight, WHR, blood pressure, glucose tolerance, and plasma catecholamines were comparable between the 2 groups.”
In conclusion, this study showed that kinetic analysis of postprandial energy expenditure can be used to examine the determinants of the time course of the thermic effect of food in man.
In addition our findings suggest that amplitude and duration of this effect are independently determined by various demographic and anthropometric factors.
Not that anyone found this of particular interest: according to Google Scholar, this paper has only been cited 7 times.
In a paper by Jean-Eric Tarride (McMaster University) that we just published in ClinicoEconomic and Outcomes Research, we examine data from all Ontarians who participated in the Canadian Community Health Survey (CCHS), cycle 1.1 and provided consent to data linkage were linked to three administrative databases.
Obese adults, and to a lesser extent overweight adults (together about 50% of the population), were more likely to report physician-diagnosed comorbid conditions, to use medications, and to have a lower health-related quality of life.
After adjustment for for personal income, smoking status, physical activity status, age and gender, the hospitalization and physician costs were respectively 40% and 22% higher among obese and overweight adults than among normal-weight adults.
No statistical cost differences were observed between normal and underweight individuals or between normal and overweight individuals.
On the other hand, health-related quality of life was significantly lower in both the underweight and obese adults when compared to normal-weight individuals.
With regard to the excess costs associated with obesity, these were not equally distributed between the genders – surprisingly enough, overall obese men did not appear to incur higher medical costs in this analysis.
“women had significantly higher physician, day procedure and hospitalization costs than men once a cost has been incurred. In addition, women had a higher probability of being hospitalized or undergoing a day procedure than men.”
Thus, we suggest that obesity programs targeted towards women may have greater potential for reducing costs associated with hospitalization, day procedures, and physicians.
Similarly, increased costs were not equally distributed across age groups – the greatest cost difference were seen in the 40–59 year old age group.
This finding suggests that obesity programs should perhaps focus their interventions on middle-aged obese individuals, which also suggests that the workplace may be the most practical environment for the implementation of such programs.
In this paper, we also point out that,
“…BMI does not truly reflect the burden of obesity-related health risks. Thus, as recently demonstrated in several large US population samples,26,27 the Edmonton Obesity Staging System (EOSS), which classified overweight and obese individuals on a 5-point ordinal scale based on the presence of medical, mental and/or functional comorbidities, strongly predicted mortality, whereas BMI did not. Importantly, in this analysis, a considerable proportion (about 50%) of individuals in the overweight range presented with obesity-related health problems (EOSS >1), while a substantial number (about 30%) of individuals with BMI >30 had no obesity-related health risks.”
It is also important to note that this paper did not look at all of the health care costs related to obesity – there were no data for medication cost or other health care costs that may have been incurred by participants – it is very likely that these costs will also be higher in obese people with associated health problems.
Reason enough to hope that with better obesity prevention and/or treatment efforts, some of these excess costs could be reduced – however, that of course, remains to be seen, as neither obesity prevention nor treatment are likely to be cheap. So far, cost savings with obesity treatment have only been shown for bariatric surgery in patients with significant health problems like diabetes (EOSS 2+).
Tarride JE, Haq M, Taylor VH, Sharma AM, Nakhai-Pour HR, O’Reilly D, Xie F, Dolovich L, & Goeree R (2012). Health status, hospitalizations, day procedures, and physician costs associated with body mass index (BMI) levels in Ontario, Canada. ClinicoEconomics and outcomes research : CEOR, 4, 21-30 PMID: 22347802