Artificial sweeteners and weight gain: examining conflicting scientific evidence

¶ … Artificial Sweetener Stimulate Appetite and Induce Weight Gain?

This paper examines the findings of four peer-reviewed scientific articles (two supporting and two opposing), on the issue of whether artificial sweeteners stimulate weight gain. Some scientific studies have reported that the use of artificial sweeteners in beverages result in weight gain, while others have argued that weight gain is actually brought about by sugar-sweetened foods and beverages. Several arguments have been put forth to support or argue against either of the sides. The article, A Trial of Artificially Sweetened vs. Sugar-Sweetened Beverages and Body Weight in Children by de Ruyter et al. opposes that artificial sweetener stimulates appetite and induces weight gain. It takes its position from the evidence provided from study conducted on normal weight children by examining the effects of artificially sweetened beverages on their weight. The results of this study indicated a negative correlation between the intake of artificially sweetened beverages and accumulation of fats and weight gain in these children. The article, Fueling the Obesity Epidemic? Artificially Sweetened Beverage Use and Long-Term Weight Gain by Fowler et al. supports the hypothesis that artificial sweetener stimulates appetite and induces weight gain. This position is influenced by the findings that there was positive dose-response correlation between artificially sweetened beverages and long-term weight gain. The article Sucrose Compared with Artificial Sweeteners: Different Effects on Ad Libitum Food Intake and Body Weight after 10 Wk. of Supplementation in Overweight Subjects by Raben et al. also opposes that artificial sweetener stimulates appetite and induces weight gain. In their study, the findings indicated that artificial sweetener supplements caused no increase in fat mass, body weight, blood pressure and energy intake in overweight individuals. Moreover, the article Saccharin and Aspartame, Compared With Sucrose, Induce Greater Weight Gain in Adult Wistar Rats, At Similar Total Caloric Intake Levels by de Matos Feijo et al. also supports the hypothesis that artificial sweetener stimulates appetite and induces weight gain. From a study conducted to examine the effects of aspartame or saccharin on weight gain in rats, the researchers found a positive correlation. This issue is of considerable importance to people's health. This is because, nowadays, more and more food companies are turning to artificial sweeteners since they are cheaper and apparently less harmful to health than sugars (which are linked to diabetes mellitus and other chronic conditions). Thus, it is important to find out which of the two sides is better supported by scientific evidence to help people make better choices.

Articles Analyses

Article 1 (Oppose) A trial of artificially sweetened vs. sugar-sweetened beverages and body weight in children

Objectives of the research study

To investigate the changes in weight gain by using a masked replacement of sugar-containing beverages with those that are non-caloric (artificially sweetened)

Brief description of the methods used to conduct the study, understanding the experimental design

The research was conducted in an eighteen-month period and it involved 641 children who were of normal weight. The oldest child was 11 years and 11 months while the youngest was 4 years and 10 months. The participants of the study were on a daily basis randomly given one of two types of beverages each of which was 250 ml. The drinks were either sugar-free (with an artificial sweetener) or contained sugars (with a total of 104 kilocalories). The beverages were given in schools. By the end of the study, 26% of the children had ceased participating in the study; however the data from those students was incorporated in some of the analyses.

Summary of the results

The Body Mass Index (BMI) of the children who were being given sugar free drinks increased by a mean of 0.02 SD units and 0.15 SD units for the children who took sugar drinks. The weight of the children who took sugar drinks increased by 7.37 kilograms compared to 6.35 kilograms for the children who were in the sugar-free group; the 95% confidence interval for the difference, -1.54 to -0.48. The waist-to-weight ratio, fat mass and skinfold-thickness measurements increased significantly for the children who were in the sugar group. There were only minor adverse events. When the final analysis was done by incorporating data from the 26% who did not finish the study, the BMI score rose by 0.06 SD units for the children who took sugar free drinks and 0.12 SD units for those who were in the sugar group (P = 0.06).

Summary of the author's conclusions

The masked replacement of sugar-sweetened beverages with non-caloric (artificially sweetened) drinks led to less fat accumulation and weight gain in children who were of normal weight.

Discussion of the strengths of the study and a clear explanation as to why these strengths increase confidence in the author's conclusions

The study found that the masked replacement of sugar-sweetened beverages with artificial sweeteners resulted in significantly less accumulation of body fat in the children. The study had a couple of strengths. First, the double-blind design removed the impact of psychological indications and the need to exhibit socially desirable behavior and enabled the sole testing of biologic processes. Even though, the blinding was not perfect, it was more effective than most double-blind methods.Testing for sucralose levels in urine samples from the participants indicated a high adherence rate. Previous studies might have resulted in non-consistent results due to lack of adherence, short study periods, smaller sample numbers and lack of stratified randomization.

This sample size was enough to allow precise results, and the one and a half year study period meant that the observed outcomes were not transient. The sample size of 461 and the individual randomization led to well-balanced study groups. After taking care of the other variables, the study assumed that all the other variables that could have an effect on body weight were the same between the groups and hence, the differences that were observed in BMI scores and the body fat scores could be largely attributed to the given beverage.

Discussion of the study's weaknesses and a clear explanation as to why these weaknesses reduce confidence in the author's conclusions

The Dutch children who participated in the study were healthy kids and most of them were whites and of normal weight. Thus, we cannot be sure if the outcome would be the same in individuals of other ethnic extractions or in children who are obese or even if the study was conducted among adults, even though the assumption is that the same biologic processes are active.

Discussion of how this study supports one side of the controversy

In the majority of observational studies, drinking of beverages that are artificially sweetened is linked to weight gain and not weight loss. That idea has constantly supported the notion that artificial sweeteners bring about weight gain, for instance some of the arguments used to support that idea is that artificial sweeteners activate the gut's sweet taste receptors. The findings of the Dutch study above do not support that notion or hypothesis. A counter argument is that individuals who are vulnerable to gaining weight may turn to artificial sweeteners in an effort to cut the amount of calories they consume. Consumers may also be of the opinion that the use of artificial sweeteners allows them to consume more of other food, however this may result in an overall increase in caloric intake. And thus whatever the argument put forward, the epidemiologic correlation between weight gain and consumption of foods containing artificial sweeteners show that switching to sugar-free (artificially sweetened) beverages is in itself not a sufficient move to tackle weight gain (de Ruyter et al., 2012).

Article 2 (Oppose) Sucrose relative to artificial sweeteners: different effects on ad libitum food intake and body weight after 10 wk of supplementation in overweight subjects

Objectives of the research study

The research study examined the impact of long-term supplementation of foods and drinks containing either artificial sweeteners or sucrose on ad libitum food consumption and body-weight in subjects who were overweight.

Brief description of the methods used to conduct the study

For a period of ten weeks, overweight women and men had a daily intake of supplements of either artificial sweeteners (BMI (in kg/m2) =27.6, n=20) or sucrose (BMI=28, n=21). On average artificial supplements provided 0 gram sucrose/d and 1.0 MJ while sucrose supplements provided 152 grams sucrose/d and 3.4 MJ.

Summary of the results

After a total of ten weeks, the group that was taking sucrose supplements had recorded increases in total energy, sucrose (up by 28%) and total energy (up by 1.6 MJ/d). The group had also recorded increases in carbohydrates consumption. The same group recorded decreases in protein and fat intakes. The artificial sweetener group recorded only minor but important decreases in energy density and sucrose intake. Increases in fat mass and body weight were recorded in the sucrose group (by 1.3 kg and 1.6, respectively), while the sweetener group recorded reductions of 0.3 kg and 1.0 respectively); the differences between groups were significant at P < 0.01 for fat mass and P < 0.001 for body weight. Diastolic and systolic BP (Blood pressure) reduced in the sweetener group by (1.2 and 3.1 mm Hg, respectively) and increased in the sucrose group (by 4.1 and 3.8 mm Hg, respectively).

Summary of the author's conclusions

The overweight participants who had huge intakes of sucrose (28% of energy), mostly as drinks, recorded increased fat mass, body weight, blood pressure and energy intake after ten weeks. These observed effects were not the same as those of similarly overweight subjects who took artificial sweetener supplements.

Discussion of the study's strengths and a clear explanation as to why these strengths increase confidence in the author's conclusions

This is perhaps the only long-term intervention research that has been compared the effects of sucrose and artificial sweeteners and concluded that the effect came from fluids. The energy derived from fluids is has been found to be less satisfying than that from solid foods (40). Therefore, fluid energy might not be completely compensated for, and this make it somewhat easier for one to over-consume energy (calories) when he or she is consuming fluids compared to when consuming solid foods (40). This conclusion is in agreement with another retrospective study in children, released recently, that revealed that consumption of beverages that are sugar-sweetened increases the risk of one becoming overweight (41). However, this current study and the children study conclusions are not similar to those released from the CARMEN intervention study, however, the difference in outcomes might be due to the difference in the quantity of sugars from fluids relative to solid foods.

Discussion of the study's weaknesses and a clear explanation as to why these weaknesses reduce confidence in the author's conclusions

Several short-term studies had supported the hypothesis that the intake of artificial sweeteners can result in increased appetite via cephalic stimulation (for example, the sight, taste and smell of food) and that sweeteners such as aspartame might have an indirect appetite stimulation effect. This long-term study did not come to such a conclusion, to the contrary, it revealed that the group that consumed artificial sweetener supplements actually had a decrease in body-weight, and that even those 70% of that decrease was attributed to loss of FFM (likely water and glycogen), 0.3 kg of fat mass was also lost. One of the reasons put forward to support this conclusion was that weight loss likely resulted by replacing high-energy sugar-sweetened foods and drinks with low-energy artificial supplements resulting in lower total energy density of the participants' diet. The reduction in energy consumption by the sweetener group was however minor and insignificant

Discussion of how this study supports one side of the controversy

In summary, predominantly female overweight participants who were provided with sucrose supplemental foods and beverages for the ten weeks ended up recording increased total energy intake, blood pressure, fat mass, and body weight. The outcome was however different in the group whose subjects were given artificial sweetener supplemented food and beverages. The most likely argument for the differences between the two groups is the use of huge amounts of beverages resulting in the subjects who had sucrose supplements over consuming energy. Thus, for overweight individuals who want to cut weight, they might want to consume only beverages that are sweetened using artificial compounds instead of those that are sucrose-sweetened (Raben, et al., 2002).

Article 3 (Support) Saccharin and aspartame, compared with sucrose, induce greater weight gain in adult Wistar rats, at similar total caloric intake levels

Objectives of the research study

The objective of this study is to evaluate the long-term changes in energy intake and weight gain through supplementing the diet of rats with either aspartame or saccharin compared to sucrose, in the presence of chow's ad libitum ingestion.

Brief description of the methods used to conduct the study, with enough detail to understand the experimental design

Utilizing the rat design, this study compares the correlation between the effect of aspartame and saccharin to sucrose in caloric intake and body weight. The study involved 29 Wistar rats. The rats were supplemented by 0.4% aspartame, 0.3% sodium saccharin, 20% sucrose, in addition to water and chow ad libitum. The physical activity of the rats was restrained. Measurements of total caloric intake, total body weight gain, caloric intake of sweetened chow and sweetened yoghurt were done after 12 weeks.

Summary of the results

Results showed that supplementation of the yoghurt with either aspartame or saccharin brought about weight gain relative to supplementation of the yoghurt using sucrose. However, total energy consumption was the same among all the rat groups. In the beginning of the experiment, the body weight of the rats was similar among all groups, however after a mixed model analysis, the groups which consumed aspartame or saccharin recorded greater weight gain compared to the group which consumed yoghurt with sucrose. An ANOVA analysis revealed that total weight gain in the group that consumed yoghurt supplemented with saccharin was 28% higher (p < 0.003), while in the aspartame group it was 20% higher (p < 0.04) compared to the sucrose group. Total caloric intake was the same for all groups in the 12-week study. Average cumulative weekly caloric intake was corrected utilizing rat weight and was also the same among all groups.

Summary of the author's conclusions

In summary, higher weight gain was recorded in the Wistar rats that had their meals supplemented with artificial sweeteners such as aspartame or saccharin, compared to those that took sucrose-supplemented yoghurt. And the weight gain was in no way associated with the caloric intake. The researchers suggested that the weight gain might have been due to a reduction in energy expenditure (due to lack of physical exercise) or increased liquid retention.

Discussion of the study's strengths and a clear explanation as to why these strengths increase confidence in the author's conclusions

The conclusions made in the research were in agreement with a study by researchers Davidson and Swithers (2008) that used Sprague-Dawley rats. Davidson and Swithers found that the rats indeed gained more weight using saccharin relative to glucose, in spite of a similar cumulative calorie intake in the 5 weeks the study was done. The outcome of this current study was also in agreement with another study conducted by Polyak (2010)et al. study, in which inbred mice with free chow had artificial sweeteners (aspartame or saccharin) added to their drinking water and the results were compared between those mice and others who had only pure water during the entire 25-week study period. The Polyak study found that the mice that were exposed to artificial sweeteners in water recorded more weight gain compared to those that were only drinking pure water, in spite of the same cumulative energy intake. All of these studies have consistently found that positive energy compensation in chow consumption occurs among the rats that were exposed to artificial sweeteners, however the increases in weight observed in these rats was not accounted for, by caloric intake since it was similar among all the three groups.

Discussion of the study's weaknesses and a clear explanation as to why these weaknesses reduce confidence in the author's conclusions

The explanations for weight-gain in aspartame and saccharin groups without increasing caloric intake are still largely speculative. For the current study, the weight gain in those groups could not be attributed to technical bias since the researchers strictly controlled the yoghurt and chow intake. A possible scientific reason could be due to the decrease in energy expenditure brought about by artificial sweeteners. Researchers Davidson and Swithers (2008) measured the core body temperature of the rats they were studying and noticed that it rose acutely a few minutes after the consumption of glucose-sweetened foods compared to non-sweetened foods, that was however not the case when saccharin was used. The researchers argued that food consumption stimulates a reflexive cephalic stage thermogenic response. Moreover, that the production of heat may be mediated by oro-sensory stimuli that may indicate presence of nutrients in the gut. However, no conclusion was made concerning the long-term effects of using saccharin.

Discussion of how this study supports one side of the controversy

This study reported a significantly higher weight gain among artificial sweetener supplemented Wistar rats compared to the rats whose diet was supplemented with sucrose. This increase was not attributed to the increase in cumulative energy intake. The difference raises the argument that the weight gain in the (aspartame or saccharin) fed rats might have been because of reductions in energy expenditure. Other studies might be required to investigate energy expenditure after exposure to artificial sweeteners and clinical trials to examines weight gain increases in human subjects (de Matos Feijo, et al., 2012).

Article 4 (Support) Fueling the Obesity Epidemic? Artificially Sweetened Beverage Use and Long-term Weight Gain