Maintaining a healthy weight isn’t easy. But according to major health experts, doing just that may decrease one’s chances of developing serious, chronic health problems. Achieving and maintaining a healthy weight is one of the "Dietary Guidelines" recommended by various ministries of health throughout Asia.

Although it is important to avoid being too thin, many Asians today are fighting the "battle of bulge". Estimates of overweight in Asia range from 5-25% - significant increases from just a decade ago thereby increasing the risk of developing high blood pressure heart disease, stroke, diabetes, certain cancers and other illnesses.^1-4

Unfortunately, there are no simple formulas or quick solutions to weight loss. But most people can successfully manage their weight by improving their lifelong exercise and eating habits. In general, people lose weight when they burn more calories than they consume. Therefore a sensible weight control program includes regular physical activity and reduced consumption of foods high in calories. A steady loss of one-half to one pound a week is recommended, rather than crash diets or other extreme approaches that severely limit amounts or types of foods.

Intense (low-calorie) sweeteners can play a useful role in helping persons to maintain a healthy weight by providing good tasting alternatives to foods and beverages typically higher in calories. According to the American Dietetic Association (ADA) "sweeteners have a role within the context of a diet consistent with the U.S. Dietary Guidelines for Americans". The ADA further says, "low-calorie sweeteners can and should be used in the context of a sensible weight management program where they can aid control of caloric intake by providing palatable food with reduced energy".⁵ The American Institute of Food Technologists also has concluded that, "attractive, good-tasting, low-calorie, low-fat foods . . . and ingredients can fit into a nutritionally balanced weight loss/weight control regimen".⁶

Although scientific testing of intense sweeteners is complex, significant progress has been made in recent years in studying their impact on appetite and body weight. This review highlights major studies in the field and summarises their implications for weight management. Because of its widespread use and its ability to replace sugars, most investigations have involved the low-calorie sweetener aspartame.

Intense sweeteners can replace nutritive sweeteners in most foods at a caloric saving of approximately 16 calories per teaspoon. Thus, caloric reduction may be achieved when low-calorie sweetened foods and beverages are substituted for their full-calorie counterparts. Questions arise, however, when one considers whether sweetener users change their eating patterns.

In pioneering work at Columbia University, Porikos et al. conducted three separate studies in which volunteers were housed on a metabolic ward for up to three weeks with the stated purpose of doing blood and other tests.^7-10 The protocols varied only slightly in duration and volunteers’ gender and weight status. During a baseline period subjects were allowed to eat as much sugar-sweetened food as they liked. Researchers then covertly substituted aspartame for sugar in a variety of foods and beverages eaten ad libitum by the patients. In all three studies, results showed that volunteers consumed approximately 15 percent fewer calories over time than on their baseline diets.

Tordoff and Alleva examined whether low-calorie sweeteners influence food intake and body weight in free-living, normal-weight men and women.¹¹ For three weeks, subjects were required to consume 1.2 litres daily of regular or aspartame-sweetened soft drink being consumed. Results showed that individuals drinking diet sodas consumed significantly fewer calories than those drinking regular sodas or the control group, which drank no soft drink at all. Weight status was unchanged in females, while males lost a small amount of weight.

While subjects in the aforementioned studies were unaware of the caloric content of the foods and beverages being consumed, in real life, people do know when they are eating low-calorie sweetened foods. Thus, it has been suggested that individuals may knowingly overcompensate for such products by eating other calorically-dense foods; for example, consuming a diet soft drink with a piece of cake.

An indirect way to determine whether use of intense sweeteners results in caloric savings is to examine food intake records from national nutrition surveys. Using USDA nutrition survey data, Smith and Heybach compared the caloric intake records of persons consuming aspartame-sweetened foods and beverages with caloric intakes of non-aspartame users.¹²

Aspartame users consumed an average of 165 fewer calories per day than non-users. Female aspartame users aged 35 to 50 years consumed 215 fewer calories per day than their study counterparts.

Kanders et al. measured weight loss, perceived feelings of energy and well-being, and other "quality of life" parameters among 59 free-living, obese men and women who were knowingly on a weight-control program for 12 weeks.¹³ The experimental group was encouraged to use intense sweeteners, while the control group was told to avoid all such products. Both groups participated in a weight loss strategy that included support groups, behaviour modification and exercise instruction.

Participants consuming aspartame-sweetened foods reported increased energy levels and positive feelings of well-being. Although there were no significant differences in weight loss between the experimental and control groups, females using aspartame-sweetened products lost slightly more weight on average. The researchers concluded that aspartame facilitated the dieters’ compliance and made weight loss more pleasurable by providing sweet foods without the calories. Preliminary results of a one-year follow-up study also indicate that aspartame does not increase weight and facilitates weight loss and maintenance when the intense sweetener is substituted for sugar.¹⁴

In a larger study, these authors placed 163 obese women on a 19-week multidisciplined weight loss program which included a balanced deficit diet and behaviour modification. The women were randomly assigned to either consume or abstain from foods sweetened with aspartame.

While both groups lost an average of 10 percent initial body weight, those consuming aspartame were more successful in keeping the weight off in the long term. After three years, the no-aspartame group had, on average, regained all the weight. However, the aspartame group had kept about half off, maintaining a medically-significant average weight loss of 5 percent initial body weight.^15,16

In an epidemiological study, Stellman and Garfinkel found that saccharin users gained an average 0.6 to 1.5 pounds (0.3 - 0.7 kilograms) more than non-users over the course of a year.¹⁷

However, this widely-publicised retrospective study was originally designed to examine cancer incidence and not weight and it failed to determine subjects’ caloric intakes or their exercise habits. In addition, it is possible that the weight gained by saccharin users, which was statistically significant but biologically irrelevant, might have been greater without the use of the intense sweetener.

A published critique also faulted the study for many other methodological problems including relying on subjects’ memory to determine weight changes and sweetener use; and excluding women who had followed a weight-loss regimen.

The authors or the critique concluded that "data of Stellman and Garfinkel do not support the conclusion that intense sweeteners may promote weight gain". They stated, "Furthermore, data from well-designed clinical trials have shown that aspartame is not associated with weight gain, and when used as part of a balanced deficit diet can facilitate weight loss".¹⁸

It also has been suggested that low-calorie sweeteners may stimulate appetite, thereby increasing food intake and promoting weight gain. To test such a hypothesis, studies have been conducted using intense sweeteners in both foods and beverages, and in capsules.

Blundell and colleagues conducted a subsequent study using solutions sweetened with aspartame, saccharin and acesulfame-K.²⁰ Although increased appetite ratings were again observed for all three types of solutions, there were no increases in actual food intake when measured one hour later.

In another study, Canty and Chan found that high-intensity sweeteners did not raise hunger levels or food consumption. Three hours after a standard breakfast, participants consumed either water or a drink sweetened with aspartame, saccharin or sucrose. Hunger levels varied at 15 and 45 minutes after the drinks, with hunger ratings highest for water, lower for non-caloric sweeteners and lowest for sugar. Hunger ratings were not affected for the rest of the day or at a buffet lunch provided an hour after the drinks. Food intake at lunch was not affected by sweetener.²¹

Birch et al. studied the effects of an aspartame-sweetened beverage on appetite and food intake in 2-to-5 year old children.²² Intake of various snack foods offered ad libitum was measured at several intervals up to one hour after consuming the solution. Snack consumption was decreased thirty minutes after drinking the aspartame-sweetened beverage as compared with consumption by those who drank water.

A similar study of 9 to 10 year old children was conducted by Anderson et al. at the University of Toronto.²³ Fruit-flavoured drinks containing sodium cyclamate, aspartame, or sucrose were given, followed by a buffet lunch 90 minutes later. Aspartame did not affect hunger or food intake when compared with sodium cyclamate or sucrose-sweetened drinks.

Several studies of adults also have shown that familiar aspartame-sweetened beverages do not affect short-term appetite or food intake when consumed before lunch or with meals as compared to water.^{24, 25} Black et al. tested the effects of various volumes of aspartame-sweetened soft drinks on hunger ratings and food intake in adult males.²⁶ Consuming 280 millilitres, or one can of diet soft drink, had no affect on appetite or food consumption compared to mineral water. However, consuming two cans of diet soft drink significantly reduced appetite rates, but not actual food intake. A follow-up study revealed that total volume of fluid consumed, not aspartame, was responsible for suppressing short term hunger in adult males.²⁷

Mattes gave adult, non-dieting volunteers equicaloric breakfasts of unsweetened cereal or cereal sweetened with sucrose or aspartame for five days, during which hunger and energy intake were monitored.²⁸ Neither aspartame nor sucrose alone significantly affected hunger ratings, intake of the next meal, daily calories consumed, or food selections. Although half of the 24 subjects were aware of the caloric content of the cereal, it did not significantly affect their intakes.

Rolls et al. covertly substituted aspartame for sugar in gelatins and puddings, creating a difference of about 200 calories between the two types of foods.²⁹ Non-dieting, normal-weight adults were given large portions of either a regular or low-calorie pudding or gelatin dessert to eat ad libitum. All individuals ate similar weights of the regular or reduced-calorie desserts. Awareness of the foods’ caloric content did not affect appetite or food consumption from a buffet offered two hours later.

Recently, Drewnowski et al. studies the effects of aspartame on energy intake in both normal-weight men and women and, in a similar study, in obese and lean women.^{30, 31} In both studies, subjects were divided into groups and given one of four different breakfast preloads of soft white cheese (fromage blanc). Two provided 700 calories and contained either sucrose or aspartame with maltodextrin, and the other two provided 300 calories and either contained aspartame or were unsweetened. Taste preferences and motivational ratings were measured throughout the day and food intake was measured at a buffet-style lunch, snack and dinner.

By studying these four different preload types, Drewnowski was able to test both the effect of substituting aspartame for sucrose while maintaining sweetness, and the effect of adding aspartame for sweetness.

In both studies, increased motivational ratings were noted at noon for those who had low energy preloads, regardless of sweetness, though these ratings were not affected during the rest of the day.

In the study of obese and lean women there were no significant differences in lunchtime food intake between preload types. In the study of normal-weight subjects, a slight increase in food intake was recorded at lunch for those who consumed the low-energy preloads. However, no overall compensation was observed, so those who consumed the low-energy preloads had a lower caloric intake for the day than those who consumed the high energy preloads.

The authors concluded that neither the addition of aspartame nor the substitution of aspartame for sucrose increased overall hunger ratings or food intake.

However, other studies involving encapsulated aspartame at much higher does have not replicated such findings. Anderson et al. administered aspartame capsules with water 60 to 105 minutes before lunch and found no effect on food intake or ratings of mood or hunger.^{33, 34} Leon and Hunninghake gave healthy adults aspartame or placebo capsules daily for 24 weeks as part of a long-term aspartame safety study.³⁵ Body weights of those taking the aspartame capsules did not differ significantly from baseline after six months.

A variety of studies in both controlled laboratory environments and free-living populations indicate that low-calorie sweeteners do not have a paradoxical effect on appetite and can produce a caloric deficit that can result in weight loss.

In a comprehensive scientific literature review, Rolls concluded that "Intense sweeteners have never been found to cause weight gain in humans…Although several investigators have reported increases in rating of hunger associated with aspartame, most have found that aspartame is associated with decreased or unchanged ratings of hunger.³⁶

In the end, losing or maintaining a healthy weight depends on the individual. No scientific research will definitively prove that consuming any particular type of sweetener or food will make people lose weight, apart from other lifestyle and motivational factors.

Successful weight management involves a multidisciplinary approach of diet, exercise and behaviour management. ^{2, 37} No product, approach or diet plan alone can be successful.

Low-calorie sweeteners are not a panacea. They do, however, enable a wide range of food choices that can aid individuals in managing their caloric intake. Because intense sweeteners provide the pleasure of sweetness, they can facilitate compliance to calorically-restricted weight loss regimens. Within a sensible weight management program, low-calorie sweeteners can play an important role in helping Asians win the "battle of the bulge".

Scientific testing of the effects of high-intensity sweeteners on hunger and weight management is extremely complex. The design of each study must address the particular research questions being asked; no single approach is appropriate in every case. Therefore, when examining the results of studies involving low-calorie sweeteners and food intake or body weight, it is important to note the following elements:

• What type and dose of low-calorie sweetener is being use in the experimental design? Is the amount of sweetener being tested comparable to that normally available in the food supply?
• How is the sweetener being administered, e.g. in foods, beverages, capsules?
• What is the time between administration of the sweetener and measurement of its affects?
• Are study volunteers normal weight or obese?

In addition to the design of the study itself, weight loss can be affected by heredity, exercise, social support, cultural conditions, environment and a variety of other external conditions. Thus, consumption of low-calorie foods and beverages is only one factor that can affect a study’s outcomes.