Finally, the Answer to Which is Better, Low Fat or Low Carb?

Timothy Boyer Ph.D.'s picture
Low fat vs low carb dieting

Do you argue with your friends over which diet is better, low-fat or low-carb? Then here's the final answer to a dieting question that has been as divisive as our politics.


A new study that pitted the low-fat diet against the low-carb diet for weight loss with a focus on whether a person's genetics and their insulin levels could be predictive of which diet is better for them, was published in the journal JAMA recently and appears to have an answer to this dieting question: both work about the same, regardless of dieters' genotype and insulin abilities.

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According to Stanford Medicine News, lead study researcher Christopher Gardner, PhD, professor of medicine, the answer to discovering successful weight loss may not be about finding that one perfect diet for everyone, but rather, making dieting more customized.

"We've all heard stories of a friend who went on one diet-it worked great-and then another friend tried the same diet, and it didn't work at all…It's because we're all very different, and we're just starting to understand the reasons for this diversity. Maybe we shouldn't be asking what's the best diet, but what's the best diet for whom?"

Very Low Calorie Diet Warning

Here's a YouTube video about the study:

The Overall Study

1. Roughly a 50:50 mix of 609 participants between the ages of 18 and 50 were randomly selected for a low-carbohydrate or low-fat diet lasting one year.

2. Each individual was tested at beginning of the study to determine whether their genetics or their insulin response could be associated as predictors of weight loss by the end of the study.

3. In the first eight weeks of the study, participants were told to limit their daily carbohydrate or fat intake to just 20 grams, and then increase the amount slightly in steps until they found an amount that they found acceptable, but still was low-carb or low-fat. Afterward, those on a low-fat diet reported a daily average fat intake of 57 grams; those on low-carb ingested about 132 grams of carbohydrates per day.

"We wanted them to choose a low-fat or low-carb diet plan that they could potentially follow forever, rather than a diet that they'd drop when the study ended," said Gardner.


4. After one year, average weight loss (in both groups) was 13 pounds; however, with a lot of variability as some lost up to 60 pounds and others gained 15-20 pounds.

5. No associations between the genotype pattern or baseline insulin levels and a propensity to succeed on either diet were found after analyzing the data.

6. Study shows that the fundamental strategy for losing weight with either a low-fat or a low-carb approach is similar: Eat less sugar, less refined flour and as many vegetables as possible.

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Of those who lost the most weight-regardless of dieting type-they attributed their weight loss to mindful eating.

"On both sides, we heard from people who had lost the most weight that we had helped them change their relationship to food, and that now they were more thoughtful about how they ate," said Gardner.

Your 2018 Weight Loss Guide Step 3: Clean Up Your Plate

Future research will focus on uncovering other data that may show differences between those who lose weight and those who don't while dieting to find some indicators/predictors for personal weight loss customization.


Stanford Medicine News "Low-fat or low-carb? It's a draw, study finds"

JAMA 2018; 319 (7): 667-679 "Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association with Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial" Christopher D. Gardner et al.

Image Source: Pixabay

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