The Keto Diet: Is it More Risk Than it’s Worth?

Low-carb diets have been popular for decades. There’s an inherent appeal in a supposedly simple diet – just cut out carbs, and watch the weight drop off – but simplicity can be deceiving. Carbohydrates are an important part of a balanced diet, so isn’t there some risk to cutting them out entirely?

Here’s a low-down on the benefits and downsides of the keto diet, largely based on a literature review on the topic.

The Good News: You Do Lose Weight

The good news is pretty much what you’d expect. Keto diets really do help you lose weight.

For example, a systematic review and meta-analysis on ketogenic diets in women with polycystic ovary syndrome found that the diet helped reduce weight, BMI, waist circumference and fat mass. The authors called for more research with larger sample sizes, but overall, the picture for weight loss looks positive.

There is some difficulty in defining what a “true” keto diet means, but generally, studies include any diet that’s high in fat and limits carbohydrate consumption to less than 50 g per day.

The Bad News: Potential Risks

But the keto diet is not completely benign either.

Perhaps the most obvious source of risk is the high fat consumption recommended by most keto diets. It might not surprise you to learn that people on a keto diet have a greater increase in low-density lipoprotein cholesterol levels compared to people on a low-fat diet. This could increase cardiovascular risk, and studies have generally been too short-term to investigate this in detail.

The source of fat could also make a difference. One study mentioned in the literature review found a U-shaped association between carbohydrate intake (as a percentage of total calories) and all-cause mortality. This means that while high-carb diets were associated with increased risk, low carb diets (less than 40% carbs) were too. Further analysis showed that animal-derived fats and proteins were associated with worse risk, while plant-based fats or proteins decreased mortality risk.

The Bottom Line

Keto diets are effective for weight loss, but not totally risk-free. Based on what we know so far, it’s best to avoid large amounts of animal-derived fats if you’re on a keto diet.