Losing Weight With Stevia

Everybody knows that cutting calories can help you lose weight. One of the first ways that many people cut calories is to reduce the amount of sugary drinks they consume. But why, if so many people are cutting sugar from their diets, are we experiencing an ever-increasing epidemic of obesity? What role do non-nutritive, no-carb sweeteners play in our nation-wide battle of the bulge? Find out about why some researchers are concerned, and if stevia can help.^{(42, 46, 47)}

Can Diet Drinks Make You Fatter?

Theories behind this weighty trend suggest that substituting low-carb, zero calorie substitutes for sugar may actually contribute to weight gain in a couple of ways:^(47-49)

• The sugar-substitutes interfere with the body's ability to utilize energy.
• They stimulate overeating to compensate for calories not delivered by no-calorie sweeteners.

Animal Studies and Statistics in Humans Suggest Zero-Calorie Sweeteners Increase Body Weight

The results of two animal studies done at Purdue University and a report in 2005 by the University of Texas Health Science Center seem to suggest diet sweeteners can make people fatter.^(47-49)

One of the Purdue studies linked using no-calorie sweeteners to a subsequent inability by rats to naturally regulate their how much they ate. The rats seemed to eat more to make up for the calories lost from using artificial sweeteners. In a later investigation by the same researchers, rats fed a diet that contained artificial sweeteners ate more and gained weight.^(48, 49)

The Purdue researchers also suggested that the body adapts to taste sensation. The taste of sweet foods triggers physiological functions that utilize the expected energy from food and sugars. In theory, consuming artificial sweeteners that activate these functions without providing energy eventually degrades this trigger. Once this happens, eating sweet foods won't trigger the physiological functions necessary to process the food properly. This would lead to weight gain and obesity:^(47-49)

What Do Clinical Studies in People Say?

Results are contradictory and mixed. Some clinical studies suggest that artificial sweeteners such as saccharin and aspartame may increase appetite. On the other hand, a 2-year study conducted by researchers at Harvard University and Beth Israel Deaconess Medical Center linked aspartame use with successful maintenance of weight loss. However, this study was partially funded by the NutraSweet Company.^(50, 51)

The University of Texas Health Science Center (UTHSC), reporting on 8 years of data in 2005, claimed that "On average, for each diet soft drink our participants drank per day, they were 65 percent more likely to become overweight during the next seven to eight years, and 41 percent more likely to become obese." Sharon Fowler, the UTHSC faculty member who analyzed and presented the data, speculated that by tricking the body into expecting calories, the artificial sweeteners were actually causing our bodies to "retaliate" and crave more calories.^{(46, 52, 53)}

Perhaps more decisively, results of a 6-month weight-loss clinical trial involving 318 overweight or obese adults who previously only drank beverages containing sugar was recently published. The study was conducted in North Carolina, and not reported as industry funded.⁽⁵¹⁾

Participants were randomly assigned to substitute 2 or more drinks a day with either water or a diet drink, or to a third control group with no substitution. The 2 groups that substituted water or diet drinks were more likely to lose weight than the control group still drinking regular sweetened beverages. In addition, when the researchers examined the diets of the participants each month, the group that were given diet drinks significantly decreased their consumption of sweet desserts.⁽⁵¹⁾

Weight Loss and Non-Nutritive Sweeteners

None of participants in the clinical trials using zero-calorie, low-carb sweeteners mentioned above lost weight during the trials. This has led some researchers to conclude that stevia doesn't help with weight loss. However, what they don't say is that the participants weren't overweight to begin with.^{(33, 35, 54)}

In fact, separating out overweight subjects from normal-weight subjects makes a difference. When researchers looked at all clinical trials measuring the effects of non-caloric sugar substitutes on body weight, replacing sugar significantly benefited BMI. Combined with the effects of stevia on blood glucose, these results suggest stevia could in fact be quite helpful for people trying to lose excess body weight.⁽⁷⁷⁾

Benefits of Stevia That May Affect Body Weight Over Time

Animal and human studies show that stevia compounds can increase insulin secretion. For example, in a clinical trial people who took stevia's stevioside compound showed an impressive 18% reduction in blood sugar and increased insulin sensitivity. Results from a clinical trial using whole stevia leaves as a sweetener showed a 35% decrease in blood sugar (postprandial) for patients with type-2 diabetes. This suggests that stevia and certain stevia compounds could also help regulate blood sugar.^{(33, 35, 43, 54, 76)}

Certainly, poor blood glucose control has been definitively linked to diabetes and metabolic syndrome. Both conditions are exacerbated by and contribute to excess body weight.^{(33, 35, 43, 46, 54)}

Clinical Evidence of Benefit

Another clinical study directly compared the effects of stevia, aspartame, and sugar-based sweeteners on:⁽⁴²⁾

• Amount of food eaten.
• Hunger and appetite satisfaction levels.
• Blood glucose and insulin levels after eating.

Participants included 19 healthy, normal-weight and 12 obese individuals. Divided into three groups, each was given a snack before lunch and dinner that contained tea and crackers with cream cheese. The snacks were sweetened with either Whole Foods 365 brand stevia, Equal, or sugar, and neither the researchers or the participants knew who was given which until after the study was completed. So how did stevia fare?⁽⁴²⁾

Dietary intake was directly measured and not based on questionairres. According to studies that associated non-nutritive sweeteners with weight gain, we could anticipate that the participants who ate these snacks would compensate by eating more food later on. But despite consuming less calories, the participants who ate snacks sweetened with stevia or aspartame did not eat more during meals.^{(42, 46, 47)}

In other words, not only were they equally satisfied with those who ate the sugar-sweetened snacks, they benefited from eating less calories by eating less sugar. Stevia also reduced glucose and insulin levels after eating, and researchers suggest that stevia can help regulate blood sugar. This would be especially helpful for diabetics and also for avoiding metabolic syndrome.⁽⁴²⁾

The Bottom Line

Though the data from the UTHSC report implies a correlation between consumption of artificial sweeteners in diet soda and risk of obesity, the study does not indicate that these sweeteners cause obesity. Observational studies do not establish causation. In fact, some argue that the association between diet drinks and weight gain may actually just be an indication that overweight people are more likely to try drinking diet beverages to lose weight. These studies also conflict with/downplay research that shows using sugar sweeteners can interfere with metabolism and cause weight gain.^{(46, 47, 55)}

Even though some insist that artificial and even stevia-derived sweeteners could cause metabolic problems and weight gain, most research says otherwise. In 2009, a review of 224 clinical studies and reports by experts from two major universities concluded that there isn't evidence that artificial sweeteners promote weight gain.^(47, 56)

There are no definitive clinical trials that support that stevia is the "magic pill" that will melt away unwanted fat or otherwise cure weight problems. But there's plenty of evidence that supports the ability of no-carb sweeteners to help achieve and maintain a healthy weight. Stevia may be the safest natural, no-carb sweetener out there. Recently the FDA granted GRAS status to one of its components as a sweetener, so look for more retail availability and studies on this unassuming little herb.^(4, 56)