As a new year comes into focus, weight loss and good health are often high on the list of goals for many

 

Marzieh Salehi, MD

According to a recent Physicians Committee for Responsible Medicine/Morning Consult survey, nearly half of U.S. adults are planning to start a new diet as one of their 2025 resolutions. Of those surveyed, 40% plan to reduce calories, 26% aim to follow a low-carbohydrate diet and 25% intend to start a low-fat diet.

While it’s promising that many are motivated to do better for their health and well-being, weight loss is complex with many biological, social and behavioral factors involved. That’s why it’s key for those embarking on a weight-loss endeavor to distinguish between myths and facts.

Read on to learn how losing weight can be nuanced rather than cut-and-dried, with insights provided by Marzieh Salehi, MD, professor of medicine, Department of Medicine, Division of Diabetes.

 

1. Myth or fact? Skipping breakfast hinders weight loss.

Answer: Veering toward myth. There are instances when skipping breakfast can create a pattern of skipping lunch and eating three times the calories in the evening, which is counterproductive. There are also studies suggesting that when skipping breakfast is associated with lower daily calorie consumption and healthier food intake, this can help with weight loss.

 

2. Myth or fact? All calories are the same whether from carbs, protein or fats.

Answer: Myth. There is merit to the notion that not all calories are the same, but studies have shown that at the same level of calories, the quality of food matters and it’s not just about calories in and out. People who eat higher-quality calories from foods high in protein, nuts, legumes, fiber-rich foods, whole grains and foods with healthier fat have been shown to be better off than those eating lower-quality foods, because higher-quality foods can change appetite and satiety via various biological factors.

 

3. Myth or fact? Cardio workouts are best for weight loss.

Answer: It depends. In general, cardio or aerobic exercise by itself may not induce weight loss. Recently, it has been shown that physical activities such as high-intensity training and a combination of aerobic exercise with isometric exercise — along with a high-quality diet and lower-calorie intake — may be more efficient in improving fat and lean body mass. High-intensity training is high bursts of any physical activity for 45 seconds to three minutes, repeated with cooling-down intervals as short as 10 minutes. Isometric exercises — like planks, wall squats and glute bridges — place tension on muscles without moving nearby joints. The bottom line is that the quality of one’s nutrient intake and the quality of exercises undertaken are key, as not all exercises can provide the same results.

 

4. Myth or fact? Slow weight loss is better and helps keep weight off.

Answer: Myth. It’s not the duration of the weight loss but the quality of the weight loss and the type of actions taken to achieve that loss. There was a randomized trial in which weight loss was induced in both a short and longer timeframe. The result was that the duration of time to lose weight didn’t seem to matter in regaining body weight. However, it should be noted that a huge rate of weight loss in a short amount of time may put some people at risk of some complications such as gallbladder disorder. Also, healthy food and water intake are necessary for safe, rapid weight loss, so those considering fast weight loss may want to consult with their physicians about their plans.

 

5. Myth or fact? Body mass index, or BMI, is a good metric to determine if weight loss is needed.

Answer: Myth. While BMI is one metric that is broadly used in clinical and research settings, it’s important to look at other metrics to get a broader picture. BMI ­— the ratio of one’s body weight over the body surface area — has served researchers well over time. But this metric doesn’t differentiate between lean mass, fat mass and bone mass. So, if someone has a larger bone mass, they may have the same body mass index as someone with more fat mass. For example, I’m currently conducting a National Institutes of Health-funded clinical trial to investigate the causes of diabetes and obesity in individuals with spinal cord injury and potential mitigatory effects of semaglutide. This medication is used to treat Type 2 diabetes and obesity. While people with spinal cord injury have a much lower body mass index, they have a much higher fat mass compared to able-bodied people, and they are at much higher risk of cardiometabolic complications because of that. The bottom line is that in individuals with BMI less than 40, other metrics — such as waist circumference or the ratio of waist circumference to hip circumference — are needed in addition to BMI to evaluate the extent of fat mass.

 

6. Myth or fact? Weight and metabolism are hereditary.

Answer: Veers toward fact. There’s no question that genetic factors matter in weight loss, but there are other important dynamics to consider like behavior carried from one generation to another. It’s well-accepted that generation-to-generation transfer of inherited characteristics can include behavioral and biological factors like food insecurity and childhood trauma. Within one generation, early childhood events can have an effect later in life with manifestations like obesity, dementia and cognitive abnormalities.

 

7. Myth or fact? Having an early cutoff time for eating aids weight loss.

Answer: Veers toward fact. There is a lot of research focusing on how circadian rhythm may improve the balance between one calorie in and one calorie out. Researchers have compared people who eat normally from 7 a.m. to 3 p.m. to people who eat from noon to 8 p.m. and it seems that having the earlier cut-off time is a bit more effective in short-term weight loss. In the clinical setting, when dealing with some glucose abnormality and diabetes control, doctors have noticed that patients who eat late have a much worse outcome in terms of glucose control. So, there may be merit to having an earlier cutoff time.

 

8. Myth or fact? Fasting helps the rate of weight loss.

Answer: Veers toward fact. There is merit to intermittent fasting for short-term weight loss, but how that translates into a long-term effect is still unknown. Depending on one’s goal, having a short-term intervention and then tying that with a mindful process for a much longer period may be durable. But as of now, all that is known is that fasting techniques such as intermittent fasting may have some short-term benefit.

Final thoughts: According to Salehi, before embarking on a new diet or exercise routine, consult with your physician to discuss any ongoing health issues and the best course of action to lose weight in a healthy way.

 


True, false or somewhere in between?

Read more in our myth-or-fact series of conversations with UT Health San Antonio faculty and care providers to test your knowledge about specific health concerns:

 

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