Medical myth-busters: Weight loss myths, busted

By Alistair Gardiner
Published January 21, 2021

Key Takeaways

  • Misconceptions abound when it comes to weight-loss strategies, and even scientific advice has been inconsistent.

  • The theory that cutting out breakfast leads to weight loss has been disproven according to current research. Data also suggests that rather than eliminating certain foods thought to put on weight or increasing foods thought to help you lose weight, focus instead on a balanced diet and exercise.

  • Claims made about weight-loss supplements are often fraudulent, and some of these products contain potentially harmful ingredients. Likewise, artificial sweeteners probably don’t result in weight loss, and could also carry health risks.

Now that the new year is in full gear, the motivated masses are busy exercising, downloading dieting apps, and meal-prepping their way to weight loss. As a doctor, you’re likely well-versed in the health risks associated with being overweight or obese—and perhaps not immune to the challenges of losing weight and keeping it off yourself.

But misconceptions abound when it comes to weight-loss strategies, and even scientific advice has been inconsistent, which can make the task all the more difficult.

Is it advisable, for example, to skip breakfast? Or does that lead to a greater appetite later in the day and, ultimately, weight gain? And what about artificial sweeteners? Cutting calories surely equates to weight loss—or does it?

Wonder no more. Here’s what the latest research says about skipping breakfast, weight-loss supplements, snacking, and more.

Skipping breakfast

The logic here is simple: By cutting out breakfast, dieters consume fewer calories and start shedding pounds. But current research suggests this isn’t the case.

A meta-analysis published in Obesity Research & Clinical Practice in early 2020 looked at 45 observational studies, analyzing associations between skipping breakfast and weight loss or gain.[]

The researchers found that skipping breakfast is associated with weight gain and obesity—and that forgoing the meal actually increases the risk of becoming overweight or obese.

In a similar vein, Nutrients published a 2019 review that examined whether skipping breakfast had associations with cardiometabolic risk factors in children and adolescents.[] Researchers, who examined 39 articles covering 286,804 individuals in 33 countries, found that roughly 95% of people who ditched breakfast were overweight or obese.

Going deeper, researchers concluded that skipping breakfast was associated with a worse lipid profile, blood pressure levels, insulin-resistance, metabolic syndrome, and a lower quality of dietary intake. The review noted that these associations did not necessarily imply causality.

But a 2019 BMJ review of studies on breakfast and body weight came to a different conclusion.[] The authors found no evidence to support the theory that eating breakfast supports weight loss or, conversely, that skipping breakfast leads to weight gain. Further high-quality trials are needed to examine the role of breakfast in weight loss, the authors concluded.

Eating fat-burning and low-fat foods

People who want to lose weight may find themselves reading promising lists of “foods that will help you lose weight” and “foods that will make you fat.” But a 2020 review published in Nutrients suggests that these rundowns should be taken with a proverbial pinch of salt—or ignored altogether.[]

So, which foods supposedly melt the fat away? The list includes pineapple, avocado, asparagus, broccoli, garlic, ginger, chili, green tea, and others.

The review found that bread, pasta, bread, dairy products, and foods containing gluten or oils often get a bad rap.

The authors, however, said these suggestions are “generally incorrect.” There are no foods with negative calories, and focusing on just a few types or ingredients isn’t a safe or effective way to lose weight. According to the authors, a multifaceted and individualized program involving a balanced diet and exercise, including follow-up over time, is the way to go.

Weight-loss supplements

Supplements are surprisingly popular. According to the NIH’s Office of Dietary Supplements (ODS), roughly 15% of US adults have used a weight-loss supplement at some point in their lives, spending about $2.1 billion on diet pills annually.

Supplements owe their success to marketing, which often makes claims like, “products reduce macronutrient absorption, appetite, body fat, and weight and increase metabolism and thermogenesis.” According to the FDA and FTC, these claims are often fraudulent. Even worse, some of these products contain potentially dangerous ingredients.

Over the past few decades, the FDA has found hundreds of products that contain hidden active ingredients typical of prescription drugs, unsafe components from drugs that have since been removed from the market, and compounds whose safety hasn’t been studied. These products often contain dozens of ingredients, sometimes close to 100.

The ODS noted that the evidence behind weight-loss supplements is inconclusive and unconvincing. The best way to lose weight, it turns out, is to follow a healthy eating pattern with a reduced caloric intake and engage in regular physical activity.


Who hasn’t heard about the perils of snacking and weight gain? Don’t buy into that belief just yet, though. The new Dietary Guidelines for Americans, 2020-2025, released by the USDA and Health and Human Services, say there is a place for snacks in a healthy eating pattern.

“For example, snacks can be used as a way to promote intake of nutrient-dense fruits and vegetables, like carrot sticks and hummus or apple slices, instead of foods like chips or cookies,” the authors wrote. “Using snacks as an opportunity to encourage nutrient-dense food group choices is especially relevant during early childhood when the total volume of food consumed at regular meals is lower and snacking is common.”

Study results have been mixed as to whether, or how much, behaviors like snacking contribute to being overweight.

Obesity and weight gain are influenced by a wide variety of genetic and environmental factors, noted the authors of a recent study published in The American Journal of Clinical Nutrition, which looked at whether genetic susceptibility to obesity is mediated by eating behavior patterns.[]

“In the present study, we found that most of the eating behavior patterns were significantly associated with obesity measures, similarly to previous studies,” the authors wrote. “The strongest associations were seen with the snacking behavior pattern and the emotional and external eating behavior pattern, and genetic factors were largely underlying these associations.”

They added that obesity prevention efforts could benefit from focusing on eating behavior change, especially in genetically susceptible individuals. “Future longitudinal and intervention studies will be beneficial to understand how eating behavior patterns and genetic susceptibility to obesity impact life-long weight outcomes,” they concluded.

Artificial sweeteners

A common impulse among dieters is to maintain their eating habits by simply moving to “diet” or “light” versions of their favorite foods. These products often replace ingredients like sugar with artificial sweeteners. But does that actually contribute to weight loss? According to studies, probably not. And, it should be noted, these artificial sweeteners carry health risks, too.

Study results are not promising when it comes to whether artificial sweeteners help with weight loss—and in fact, they may have the opposite effect.

A review published in BMJ in 2019 examined the association between sweeteners and general health outcomes.[] After analyzing the results of 35 studies, the authors concluded that there was no substantial evidence that sweeteners had an impact on overweight and obese individuals or on those actively trying to lose weight.

Other studies have found that consumption of sweeteners is associated with weight gain.

One review, published in Canadian Medical Association Journal, looked at 37 trials and studies to establish the effects of nonnutritive sweeteners (like aspartame, sucralose, and stevioside) on weight and cardiometabolic factors.[] Contrary to what you might expect, the researchers found that consumption of sweeteners was associated with a modest increase in body mass index, weight and waist circumference, and higher incidence of obesity, hypertension, metabolic syndrome, type 2 diabetes, and cardiovascular events.

Authors of another study on artificial sweeteners published in Nutrition and Obesity, noted that they “appear to change the host microbiome, lead to decreased satiety, and alter glucose homeostasis, and are associated with increased caloric consumption and weight gain.”[]

So, if these common myths teach us anything, it’s to carefully consider what you read. Sometimes, the most obvious answer—counting calories and exercise—is the right one.

What this means for you

There are many theories about what to do (or avoid) to lose weight. Research says that many of these—such as the benefits of cutting out breakfast, avoiding certain foods, or using artificial sweeteners or weight-loss supplements—are not true, and could even have harmful effects. Read the research if possible, and pass along the facts to your patients.

Read Next: Top 5 physician-recommended diets

Share with emailShare to FacebookShare to LinkedInShare to Twitter