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Low-Fat vs. Low-Carb: What’s Healthier?

Both eating approaches are touted for weight loss and big health benefits. But do they deliver?

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Whether it’s the keto diet, the Atkins approach, or any other popular way of cutting carbs, low-carb is currently one of the most popular ways to eat. At its peak popularity, 18 percent of Americans were going low-carb. However, there are also plenty of people who keep the carbs and cut the fat, following a low-fat eating approach. Since the 1960s, low-fat diets have had a strong hold on plenty of individuals. 

So, which is the best, or healthier, choice: low-carb or low-fat? 

At First Glance, Low-Fat and Low-Carb Diets Have Similar Effects

When it comes to the great low-fat vs. low-carb debate, weight loss is one of the most-touted benefits. So, it’s no surprise that scientists set out to determine if either eating approach is better than the other when it comes to losing weight and maintaining that weight loss. 

A 2010 study published in Annals of Internal Medicine tested the impact of following either a low-fat or low-carb diet over two years, combined with behavioral counseling. A total of 307 overweight participants were divided into two groups: one that followed the Atkins diet (only 20 grams of carbs per day), and one that followed a standard low-fat diet (30 percent or less of their total calories per day coming from fat).

The results were somewhat surprising. As Jonny Bowden, PhD, CNS, explains, “After 12 months, both groups lost approximately the same amount of weight (11 kilograms, or roughly 24 pounds). Both groups regained some weight during the second year, with no significant difference between the two groups. The average weight loss after two years was seven kilograms (about 15.5 pounds). As with most diet studies, some folks regain part of the weight they lose not because the diets don’t work but because people start drifting back to their old habits.”

These findings seem to suggest that there’s really no difference between low-fat and low-carb diets, at least when the goal is weight loss. But, Bowden notes, it’s not exactly that simple: “Though the media reported “no difference” between the two diets, several pieces of crucial information were left out.”

Weight Loss Can Vary No Matter Which Approach You Try

Interestingly, while the above study suggests that there ultimately may not be a big difference in your ability to lose weight depending on whether you choose to go low-carb or low-fat, more recent studies suggest that there’s really no clear-cut answer. In fact, the results can really depend on you, personally – not necessarily your diet.

For example, a systematic review by the Cochrane Collaboration looked at available evidence from 61 trials and almost 7,000 participants to determine whether low-carb or low-fat eating worked best for weight loss. Ultimately, researchers found that the two diets worked about the same. Shorter-term studies, such as those that had participants stick to a low-carb or low-fat diet for up to six months, saw the low-carb group lose about two additional pounds of weight (a statistically insignificant amount). Longer-term studies, which lasted anywhere from one to two years, saw little to no difference in weight lost.

The most important finding from this review? While most studies looked at weight loss for whole groups, the results actually varied quite significantly from individual to individual. A low-fat approach worked better for some participants and not at all for others; a low-carb approach had similar effects. This suggests that there really is no one “best” or “healthiest” diet for every individual. 

How Low-Fat and Low-Carb Diets Can Affect Overall Health

While weight loss often catches the most attention when it comes to the debate over low-fat vs. low-carb eating, these diets can affect your health and wellness in other ways. 

For example, that 2010 study discussed above may have showed “no difference” in weight loss, but there were bigger health implications. As Bowden explains, “While weight loss was similar, the low-carb group had better cardiovascular results. At the end of six months, the low-carb group had lower triglycerides, lower VLDL (very low density lipoprotein) cholesterol and lower diastolic blood pressure. These differences between the diet groups equaled out by the end of the study, but one important difference that did not even out was HDL (“good”) cholesterol. The low-carb group had significantly higher (23 percent higher, to be exact) HDL cholesterol throughout the entire two years of the study.”

This suggests that a low-carb eating approach may have some connection to an increase in HDL (or “good”) cholesterol levels, while a low-fat diet may not.

Additionally, going low-carb – and upping your protein intake – may have beneficial effects on your mood and your hunger level. Two studies, one from 2005 and one from 2007, suggest that low-carb diets can offer these perks better than low-fat diets. This is likely because high-protein diets are more filling, and eating plenty of fat can help curb your appetite. 

And when it comes to blood pressure, research suggests both low-carb and low-fat diets may be able to reduce blood pressure levels for the short-term. 

So, there’s really no one “healthy” approach. Depending on your unique health needs, your success with different eating approaches and nutrition focuses will vary. As Bowden suggests, “The best diet is the one you stick with and the one you have support in doing.”