How keto, Paleo and Atkins diets could shorten your life, and what to eat instead

Low-carb diets are popular because they are said to reduce the risk of heart disease and diabetes, but new research shows those heavy on meat and cheese are deadlier than a high-carbohydrate diet

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A butcher’s stall at a Beijing market. A low-carb diet that relies too much on meat as a source of protein has been linked to a shorter lifespan. Photo: AFP

Published: 3:00am, 25 Sep 2018Updated: 1:51pm, 14 Dec 2020

Have you been living a low-carb life? Diets that replace carbs with protein or fat – think Atkins, South Beach, Paleo, keto – are popular largely based on claims that they lead to weight loss and reduced risk of cardiovascular disease and Type 2 diabetes. However, new research suggests that replacing carbohydrates with animal fat and protein, as most low-carb diets do, is linked to a shorter lifespan.

Many randomised controlled trials – typically the gold standard in research – have found short-term benefits for weight and health with low-carb diets, although that’s not a given. Because they were short-term studies, they haven’t been able to assess how low-carb diets affect longevity. So a team from Harvard University and the University of Minnesota looked at observational data from a large study of atherosclerosis risk.

The results, published in August in Lancet Public Health, find a potential danger in low-carb diets. Based on carbohydrate intake alone, researchers estimated that a 50-year-old participant who eats less than 30 per cent carbs will live to be 79.1 years old, compared with 82 years for someone eating more than 65 per cent carbs.

This dovetails with new research presented at the European Society of Cardiology Congress in August. Researchers from the Medical University of Lodz in Poland looked at data from 24,825 participants in the US National Health and Examination Survey collected from 1999 to 2010. Those with the lowest carbohydrate intake had a 32 per cent higher risk of dying overall compared with participants who ate the most carbs.

For longer life, say experts, get more of your carbohydrates from high-fibre fruit and vegetables, more of your fat from avocados, olives and olive oil and more of your protein from legumes, whole grains, nuts and seeds. Photo: Alamy

When the authors looked specifically at deaths from heart disease or stroke, the risk was 50 per cent higher. Lead author Maciej Banach said the data suggested that although low-carb diets might be useful in the short term, they have risks, not benefits, in the long term.

It turns out that’s not the whole story, though. To explore whether these results were due to carbohydrate intake or something else, the authors of the Lancet study examined a number of other diet and lifestyle factors known to affect health and longevity. Noting that many previous studies of carbohydrate intake haven’t factored in the effects of our other food choices, the authors homed in on exactly what types of protein and fat participants on low-carb diets were replacing their carbs with.