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Low-Fat, Plant-Based Dieting May Allow Carbs

Timothy Boyer Ph.D.'s picture
Study shows carbs do not hinder a plant-based diet.

A new study shows that eating a relatively high carb diet that is primarily low-fat and plant-based outperforms a high fat, low-carb diet when it comes to calorie counting and actual loss of body fat.


Which is Worse: More Fat or More Carb?

In a new comparison study to determine which leads to more calorie consumption—a high carb or a high fat diet—researchers found a surprising result that in spite of a diet relatively high in carbs that leads to pronounced swings in blood glucose and insulin levels, as long as the carbs come with a low-fat, plant-based diet, it appears to outperform a high-fat, low-carb diet with both a lower amount of calories consumed and a greater amount of total body fat lost.

This research was intentionally focused on determining which was worse when it came to calorie consumption: eating high-carb foods or eating high-fat foods. Previously, both were considered to lead to increased calories for differing reasons.

"High-fat foods have been thought to result in excess calorie intake because they have many calories per bite. Alternatively, high-carb foods can cause large swings in blood glucose and insulin that may increase hunger and lead to overeating," said NIDDK Senior Investigator Kevin Hall, Ph.D., the study's lead author. "Our study was designed to determine whether high-carb or high-fat diets result in greater calorie intake."

To test the caloric effect pitting carbs against fats, 20 adults were placed on either a plant-based, low-fat diet (10.3% fat and 75.2% carbohydrate) or an animal-based, low-carbohydrate (75.8% fat and 10% carbohydrate) diet for two weeks, which was then immediately followed by two weeks with the participants switching to the alternate diet. The low-fat diet was high in carbohydrates. The low-carbohydrate diet was high in fats. The participants were given three meals a day, plus snacks, and could eat as much as desired.

What researchers observed was that:

• Participants on the low-fat diet ate 550 to 700 fewer calories per day than when they ate the low-carb high fat diet.

• Participants reported no differences in hunger, enjoyment of meals, or fullness between the two diets.

• While participants lost weight on both diets, only the low-fat, high-carb diet led to a significant loss of body fat.

The significance of this is that commonly expected predictions of a carbohydrate-insulin model of obesity leading to fat accumulation and increased calorie consumption does not necessarily always hold true with respect to when making a comparison to someone on a high-fat, low-carb diet that theoretically should leave a person feeling fuller and less likely to eat more calories and hence have less body fat resulting.

"Despite eating food with an abundance of high glycemic carbohydrates that resulted in pronounced swings in blood glucose and insulin, people eating the plant-based, low-fat diet showed a significant reduction in calorie intake and loss of body fat, which challenges the idea that high-carb diets per se lead people to overeat. On the other hand, the animal-based, low-carb diet did not result in weight gain despite being high in fat," said Hall.

"Interestingly, our findings suggest benefits to both diets, at least in the short-term. While the low-fat, plant-based diet helps curb appetite, the animal-based, low-carb diet resulted in lower and more steady insulin and glucose levels," Hall said. "We don't yet know if these differences would be sustained over the long term."

Perhaps Not That So Surprising After All

Observing that a plant-based diet with a high-carb content led to more fat loss and less calories consumed perhaps should not be so surprising.

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More recently we learned in another study that when it comes to calories, just by changing your diet to a plant-based one, your body will go into an increased calorie burning mode—after meals—that is nearly 20 percent above your normal calorie burn. Furthermore, it appeared to manifest on the loss of abdominal fat.

Emaxhealth has previously provided multiple articles that show scientific evidence that a plant-based diet is among the healthiest you can choose whether for losing weight or adopting a healthier and sustainable lifestyle.

Scientific Study: Plant-Based Diet Is The Most Healthy

Six Most Popular Plant-Based Diets: Which One's Right for You?

And, when you consider that there is a significant amount of evidence that carb cravings while eating highly processed carb-based food leads to eating even more carb-based food—a viscous carb cycle if you will—that lumping-in healthier carbs with the bad carbs is a mistake, and a distinction that is not made clearly enough, often enough.

In fact, the carb-versus-fat news release also mentions that the researchers in an earlier study found that a diet high in ultra-processed food led to overeating and weight gain in comparison to a minimally processed diet matched for carbs and fat. In other words, the opposite of what they observed in this study.

Therefore, the findings may be sensible when you consider what carbs we are comparing in these studies. Especially since obesity is a relatively modern problem that has been correlated with not just the amount of food we eat, but the nature of it as well. Carb-blamed obesity 40 years ago was not the bugaboo then that it is claimed to be today.

The Dieting Experiment Continues

All of this said, today marks the day I resume my dieting experiment. The decision I have made is to go from a low-carb, high protein style diet (that has proven successful) to one that is more Mediterranean in style that will be plant-based with a normal healthy carb load allowed. The reason for this choice is that I feel now is the time to turn my dieting efforts to one that is sensibly more sustainable from what I’ve learned about dieting so far and see what happens when I put this into practice for the next two months.

Plus, I want to be able to drink wine again.

Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with an eye on the latest news, Timothy continues writing about science with a focus on what you need to know for healthier living. For continual updates about health, you can also follow Timothy on Twitter at TimBoyerWrites.

Image Source: Courtesy of Free-Photos from Pixabay


NIH study compares low-fat, plant-based diet to low-carb, animal-based diet” National Institutes of Health news release 212 Jan. 2021.

Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake” Kevin D. Hall, et al. Nature Medicine 2021; DOI: 10.1038/s41591-020-01209-1