New research being presented at this year’s European Congress on Obesity (ECO) in Venice, Italy (12-15 May), suggests that replacing sugar-sweetened food and drinks with low/no energy-sweetened products can help weight control for at least one year after rapid weight loss in adults, without increasing the risk of type 2 diabetes or cardiovascular disease.

The findings of a year-long randomised controlled trial involving adults with overweight and obesity and children in the overweight range from Northern, Central and Southern Europe also found that consumption of sweeteners and sweetness enhancers (S&SE) was associated with greater diet satisfaction, more positive mood, and less cravings and explicit liking for sweet foods in adults.

The results follow a 2023 systematic review of the evidence by WHO, which suggested that replacing free sugars with non-sugar sweeteners did not appear to help with weight control in the long term and could raise the risk of various health problems, including type 2 diabetes and cardiovascular diseases. The report highlighted uncertainty around the evidence between sweeteners and disease outcomes [1].

“Weight maintenance after weight loss is difficult to achieve, and our findings support the use of S&SEs found in many foods and beverages worldwide as alternatives to sugar-sweetened products to help manage weight control in adults with overweight”, says trial lead author Professor Anne Raben from the University of Copenhagen in Denmark. “The findings also provide important information to address the controversies about potential adverse health effects. Until now, safety data have generally come from animal studies using sweetener doses far above the usual intake in humans.”

S&SEs have very high sweetening power but contribute little or nothing to energy intake. Natural and synthesised sweeteners, such as aspartame, stevia, and saccharin, are commonly added to products by the food and drink industry to cut the sugar content, and are consumed by millions of people around the world every day, for example in soft drinks, desserts, and breakfast foods.

However, the safety of these food additives and their use in appetite and weight control has been hotly debated, and little is known about the long-term effects of S&SE on eating behaviour.

Sweeteners show promise for weight control

To provide more evidence, researchers from the SWEET (Sweeteners and sweetness enhancers: Prolonged effects on health, obesity and safety) project, conducted a one-year randomised controlled trial to investigate whether the prolonged use of S&SEs as part of a healthy low-sugar diet could improve weight loss maintenance after rapid weight loss, as well as benefit risk markers for type-2-diabetes and cardiovascular diseases compared to no S&SE consumption.

Participants also completed questionnaires (at the start of the trial and after 2, 6 and 12 months) to assess the effect of S&SEs on diet satisfaction, control overeating, explicit liking and implicit wanting for food, eating behaviour, physical activity, and quality of life.

The trial recruited 341 adults with overweight or obesity (aged 18-65 years, 71% women, body mass index (BMI) ≥25 kg/m2), and 38 children with overweight (6-12 years, 60% girls, BMI-for-age >85th percentile) from Denmark, Spain, Greece, and The Netherlands through web pages, social media, newspapers and registries.

During the first 2 months of the trial, adults were instructed to follow a low-energy diet (the Cambridge Weight Plan) with the aim of achieving at least 5% weight loss. Children received dietary advice to maintain body weight.

In the following 10 months, participants were randomised to either a healthy diet with less than 10% of energy from added sugar allowing for foods and drinks with S&SEs (S&SEs group), or a healthy diet with less than 10% of energy from added sugar not allowing foods and drinks with S&SEs (sugar group).

At the start of the trial and after 2, 6, and 12 months, participants took part in clinical investigation days to measure change in weight, in BMI-for-age z-score in children (a measure of how many standard deviations a child’s BMI is above or below the average BMI for their age and sex), anthropometry, and risk markers for T2D (e.g., glucose and haemoglobin A1c) and CVD (e.g., cholesterol). Participants also completed food frequency questionnaires and urine samples were collected to measure biomarkers of S&SEs, fructose and sucrose to measure compliance [2].

As planned, intake of sugar-rich foods and beverages declined in both groups over the trial, but significantly more in the S&SE than in the sugar group. At the same time, intake of S&SE products increased in the S&SE group and declined in the sugar group. These results were confirmed by urinary biomarker analyses.

The intention-to-treat analyses (including 277 adults who successfully lost 5% or more body weight after the 2-month weight loss period) found that those consuming S&SEs had slightly better weight loss maintenance after 1 year than the sugar group (average weight loss of -7.2kg vs -5.6 kg making a difference of 1.6 kg).

Additionally, in 203 participants who completed all clinical investigations, risk markers for type 2 diabetes and cardiovascular disease did not differ between the groups.

No differences in BMI-for-age z-score or other outcomes were noted in the 22 children who completed the trial. A larger study would be required in more children to determine any potential effect, researchers say.

Sweeteners reduce cravings for sweet foods and improve well-being in adults

In further analyses of eating behaviour, researchers found that adults in the S&SE group reported greater diet satisfaction when eating out, increased positive mood, and lower craving for sweet food at 6 months than the sugar group. In contrast, adults in the sugar group had greater liking for sweet over savoury foods at 6 months and 12 months. However, there were no differences between the groups in reported physical activity or quality of life.

In children, replacing food and drinks with added sugar with sweetened products had no impact on eating behaviour or physical activity. However, inclusion of S&SEs appeared to benefit children with high levels of uncontrolled eating (eating in response to food palatability [tastiness] and the likelihood of over-consuming).

As co-lead author Ms Clarissa Dakin from the Appetite Control and Energy Balance Research Group at the University of Leeds, UK, explains, “Our findings suggest that the inclusion of low/no energy sweetened products may benefit children who show high levels of uncontrolled eating. For these children, being allowed to consume S&SEs led to lower levels of uncontrolled eating at 12 months in comparison to the children who were not allowed to consume S&SE’s. This benefit was not found for children with lower levels of uncontrolled eating. Together, these findings provide important insights for the ongoing re-evaluation of food additive sweeteners by the European Food Safety Authority and other health agencies worldwide.”

Professor Jason Halford, Head of the School of Psychology at the University of Leeds, UK, one of the SWEET co-authors and President of the European Association for the Study of Obesity (EASO), says, “’The use of low calorie sweeteners in weight management has been questioned, in part because of the link between their use and apparent weight gain in observational studies, however, increasingly it is becoming apparent that is not the case in long term studies.”

Sustainable eating Meals based on legumes such as beans and peas are more satiating than pork and veal-based meals, according to a recent study by the University of Copenhagen’s Department of Nutrition, Exercise and Sports. Results suggest that sustainable eating may also help with weight loss.

Numerous modern dietary recommendations encourage high protein consumption to help with weight loss or prevent the age-related loss of muscle mass. Furthermore, consuming more vegetable-based protein from beans and peas and less protein from meats such as pork, veal and beef is recommended because meat production is a far greater burden on our climate than vegetable cultivation. Until now, we haven’t known much about how legumes like beans and peas stack up against meat in satiating hunger. As a result, little has been known about the impact of vegetables and the possibility of them catalyzing or maintaining weight loss.

High-protein vegetables fill more.

The recent study demonstrated that protein-rich meals based on beans and peas increased satiety more in the study participants than protein-rich veal and pork based meals. In the study, 43 young men were served three different meals in which patties – consisting of either beans/peas or veal/pork – were a key element. The study also demonstrated that when participants ate a protein-rich meal based on beans and peas, they consumed 12% fewer calories in their next meal than if they had eaten a meat-based meal.

“The protein-rich meal composed of legumes contained significantly more fiber than the protein-rich meal of pork and veal, which probably contributed to the increased feeling of satiety”, according to the head researcher, Professor Anne Raben of the University of Copenhagen’s Department of Nutrition, Exercise and Sports.

Sustainable eating can help weight loss

Most interestingly, the study also demonstrated that a less protein-rich meal based on beans and peas was as satiating and tasty as the protein-rich veal and pork-based meals.

“It is somewhat contrary to the widespread belief that one ought to consume a large amount of protein because it increases satiety more. Now, something suggests that one can eat a fiber-rich meal, with less protein, and achieve the same sensation of fullness. While more studies are needed for a definitive proof, it appears as if vegetable-based meals – particularly those based on beans and peas – both can serve as a long term basis for weight loss and as a sustainable eating habit”, concludes Professor Raben.

A new qualitative study highlights the negative interpersonal and psychological consequences associated with “yo-yo dieting,” also known as weight cycling. The work underscores how toxic yo-yo dieting can be and how difficult it can be for people to break the cycle.

“Yo-yo dieting – unintentionally gaining weight and dieting to lose weight only to gain it back and restart the cycle – is a prevalent part of American culture, with fad diets and lose-weight-quick plans or drugs normalized as people pursue beauty ideals,” says Lynsey Romo, corresponding author of a paper on the study and an associate professor of communication at North Carolina State University.

“Based on what we learned through this study, as well as the existing research, we recommend that most people avoid dieting, unless it is medically necessary. Our study also offers insights into how people can combat insidious aspects of weight cycling and challenge the cycle.”

For the study, researchers conducted in-depth interviews with 36 adults – 13 men and 23 women – who had experienced weight cycling where they lost and regained more than 11 pounds. The goal was to learn more about why and how people entered the yo-yo dieting cycle and how, if at all, they were able to get out of it.

All the study participants reported wanting to lose weight due to social stigma related to their weight, and/or because they were comparing their weight to that of celebrities or peers.

“Overwhelmingly, participants did not start dieting for health reasons, but because they felt social pressure to lose weight,” Romo says.

The study participants also reported engaging in a variety of weight-loss strategies, which resulted in initial weight loss, but eventual regain.

Regaining the weight led people to feel shame and further internalize stigma associated with weight – leaving study participants feeling worse about themselves than they did before they began dieting. This, in turn, often led people to engage in increasingly extreme behaviors to try to lose weight again.

“For instance, many participants engaged in disordered weight management behaviors, such as binge or emotional eating, restricting food and calories, memorizing calorie counts, being stressed about what they were eating and the number on the scale, falling back on quick fixes (such as low-carb diets or diet drugs), overexercising, and avoiding social events with food to drop pounds fast,” says Romo. “Inevitably, these diet behaviors became unsustainable, and participants regained weight, often more than they had initially lost.”

“Almost all of the study participants became obsessed with their weight,” says Katelin Mueller, co-author of the study and graduate student at NC State. “Weight loss became a focal point for their lives, to the point that it distracted them from spending time with friends, family, and colleagues and reducing weight-gain temptations such as drinking and overeating.”

“Participants referred to the experience as an addiction or a vicious cycle,” Romo says. “Individuals who were able to understand and address their toxic dieting behaviors were more successful at breaking the cycle. Strategies people used to combat these toxic behaviors included focusing on their health rather than the number on the scale, as well as exercising for fun, rather than counting the number of calories they burned.

“Participants who were more successful at challenging the cycle were also able to embrace healthy eating behaviors – such as eating a varied diet and eating when they were hungry – rather than treating eating as something that needs to be closely monitored, controlled or punished.”

However, the researchers found the vast majority of study participants stuck in the cycle.

“The combination of ingrained thought patterns, societal expectations, toxic diet culture, and pervasive weight stigma make it difficult for people to completely exit the cycle, even when they really want to,” Romo says.

“Ultimately, this study tells us that weight cycling is a negative practice that can cause people real harm,” Romo says. “Our findings suggest that it can be damaging for people to begin dieting unless it is medically necessary. Dieting to meet some perceived societal standard inadvertently set participants up for years of shame, body dissatisfaction, unhappiness, stress, social comparisons, and weight-related preoccupation. Once a diet has begun, it is very difficult for many people to avoid a lifelong struggle with their weight.”

The paper, “A Qualitative Model of Weight Cycling,” is published in the journal Qualitative Health Research. The paper was co-authored by Sydney Earl, a Ph.D. student at NC State; and by Mary Obiol, an undergraduate at NC State.