A series of recent studies has reignited the debate over whether drinking diet soda could be more effective than water in helping some people shed extra kilos, with researchers and nutritionists weighing in on the controversial claim. The renewed interest comes after social media buzz and resurfaced research suggesting that people drinking artificially sweetened beverages daily—rather than water—lost significantly more weight over the course of a year. The findings, however, have sparked both optimism and concern among health experts, with implications that extend to Thailand’s growing public health challenges associated with obesity and metabolic disease.
The question, “Can diet soda really be better than water for dieting?” is not just fodder for viral TikTok videos. It is relevant for millions of Thais, given the country’s rising rates of obesity, chronic diseases, and the popularity of both sweetened soft drinks and zero-calorie alternatives. A recent report in the Daily Mail summarises how claims from earlier research are being revisited amid growing public curiosity—and persistent skepticism—about artificial sweeteners and their complex impact on weight management (dailymail.co.uk).
According to this article and several referenced studies, overweight or obese adults who consumed diet sodas daily as part of a structured weight loss program lost on average twice as much weight as those who drank water. One 2015 randomized trial split participants—mostly women in their 40s—into two groups: one drank two cans of diet soda each day, while the other drank an equivalent amount of water. Both groups followed similar diet and exercise regimens for 12 weeks, with researchers providing diet sodas from major international brands. Over one year, those in the diet soda group averaged nearly 13.7 pounds in weight loss, compared to 5.4 pounds in the water group (PMC4744961, NBC News coverage).
Experts suggest the key mechanism may be that artificially sweetened drinks help people satisfy sugar cravings without the caloric cost, so they are less likely to reach for high-calorie snacks. Dr Marion Nestle, a prominent nutritionist at NYU Langone, explained to the Daily Mail: “Weight gain is the result of eating more calories than are expended in metabolism and physical activity. Anything that reduces calorie intake, from any source, should help. Neither water nor diet sodas have calories, but diet sodas have chemical sweeteners that might encourage eating more food. Studies on the effects of diet soda are mixed. Water, by definition, is neutral.”
Another expert, a bariatric surgeon from a leading medical center in Mexico, noted, “Research showing that people using artificially sweetened beverages actually lost more weight than those drinking water surprises people, but it lines up with what I see in practice. For some patients, that familiar sweet taste keeps them compliant. They’re less likely to binge later, less likely to feel deprived, and more likely to stick to the plan. It’s not about the Diet Coke doing something magical, it’s about it preventing something destructive.”
Despite such findings, there are critical caveats. The earlier studies had relatively short follow-up periods and often included participants with an existing habit of drinking diet sodas. When the same research protocol was repeated in 2023 at Liverpool University, the observed weight loss advantage from diet sodas shrank and became statistically insignificant, especially when people without sweet beverage cravings participated. This highlights the potential role of individual variation in craving and consumption patterns (biolayne.com).
Moreover, Caroline Susie, a registered dietitian and spokeswoman at the Academy of Nutrition and Dietetics, emphasized that “water is still the ‘gold standard’ for hydration and weight loss,” but also acknowledged that “when low- or no-calorie sweetened beverages replace higher-calorie drinks, they can help reduce overall energy intake, which supports weight loss. For people who are trying to reduce sugar but still want flavor, sweetener-infused beverages may help them stay on track and avoid higher-calorie alternatives.”
On the local Thai front, these insights are particularly important. Thailand has one of the highest rates of sugar-sweetened beverage consumption in Southeast Asia, contributing to rising obesity, diabetes, and heart disease rates. The Ministry of Public Health has introduced sugar taxes and promoted low-calorie alternatives, but concerns about artificial sweeteners persist. Thai beverage aisles—from convenience stores in Bangkok to highway rest stops—are well stocked with both regular and diet sodas, underscoring the significance of clear guidance for consumers.
Despite the potential for diet sodas to support weight loss under certain conditions, the broader scientific consensus remains cautious. Several large-scale reviews and meta-analyses, including a notable 2022 review of 17 studies, found that replacing sugary drinks with non-nutritive sweetened beverages may result in only modest weight changes—with effects likely less pronounced outside of tightly monitored diet programs (Harvard Health Blog, Rutgers). Furthermore, experts warn of long-term health risks, especially with high and prolonged intake of artificial sweeteners such as aspartame and saccharin. These sweeteners have been scrutinized for possible links to cancer, disrupted glucose metabolism, increased risk of type 2 diabetes, and even negative changes in gut microbiome composition (Wikipedia - Artificial sweetener).
A Canadian dietitian for MyHealthTeam pointed out: “Choosing diet soda instead of water could reinforce a preference for sweet flavors, which may affect appetite regulation or lead to seeking out other sweet foods. Water tends to promote a more neutral palate and a natural connection with thirst and hunger cues. Over time, these could influence someone’s relationship with food and overall lifestyle. There’s also growing research that artificial sweeteners could negatively alter the gut microbiome. Gut microbiome health is associated with weight, where gut imbalances could be playing a factor in obesity and make weight loss more difficult.”
The World Health Organization (WHO) has also highlighted weak and inconsistent evidence on the benefits of non-sugar-sweetened beverages for weight control, warning that most studies are short-term and may not reveal adverse effects that emerge over years (WHO non-sugar sweetener guideline). Accordingly, regional health authorities, including the Thai Food and Drug Administration, recommend moderation and a focus on overall dietary quality rather than reliance on diet drinks.
For Thai society, the use of artificially sweetened beverages intersects with cultural preferences for sweetness, marketed perceptions of “diet” and “health,” and the rise of non-communicable diseases. Street vendors often offer both sugary and low-sugar versions of popular drinks, reflecting both consumer demand and health policy nudges. Experts at a leading Bangkok medical university noted that while limited use of diet sodas might offer short-term advantages for people struggling to reduce sugar intake, “the long-term solution lies in shaping healthier habits rather than substituting one sweetener for another.”
Looking to the future, investigations continue into how individual factors—such as genetics, habitual diet, gut microbiome, and psychological responses—determine whether a person is likely to benefit or suffer from swapping water for low-calorie drinks. Until there are clearer answers, the prevailing medical advice remains rooted in moderation, self-awareness, and a focus on sustainable, balanced eating patterns. Dr Nestle’s succinct guidance resonates: “Weight management is about the whole diet, not individual foods or drinks.”
Practical recommendations for Thai readers include using diet sodas occasionally as a transitional tool to help reduce sugar cravings when cutting back on sweetened beverages, but not as a primary or long-term substitute for water. Staying hydrated with clean water, increasing intake of fruits, vegetables, and whole foods, and limiting all sweetened beverages—artificial or natural—remains the most effective and safest health strategy. For those with specific health concerns, consulting a healthcare professional is strongly advised before making significant dietary changes. Importantly, the debate over diet sodas versus water illustrates the evolving science of nutrition—and the need for each individual to find an approach that fits both their lifestyle and long-term well-being.
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