The investigative journalist Gary Taubes is known for his painstakingly researched and withering demolitions of the “eat less, move more” diet orthodoxy, but his latest book is personal. The Case for Keto is aimed at “those of us who fatten easily”. Taubes locates himself in this beleaguered group, “despite an addiction to exercise for the better part of a decade” and a diet of “low-fat, mostly plant ‘healthy’ eating”. “I avoided avocados and peanut butter because they were high in fat and I thought of red meat, particularly steak and bacon, as an agent of premature death. I ate only the whites of egg.” Yet still he remained overweight.
Taubes started to shed those pounds when he realised that one-size-fits-all diet advice fails, among other reasons, because people are metabolically different. Some of us can eat fattening carbohydrates and sugar and get away with it; others can’t.
Those who claim to have “a sluggish metabolism” are too often seen as making lame excuses for their weakness and indulgence. This punitive view – that fat people could easily be thin people if only they would eat less and exercise more diligently – is wrong, says Taubes. It amounts to what the philosopher Francis Bacon called “wishful science”, based on “fancies, opinions and the exclusion of contrary evidence”.
More likely, people who are perpetually fighting to lose weight have “a metabolic disorder of excess fat accumulation”. They store fat when they ought to burn it for energy. They become “insulin-resistant”, meaning that their insulin levels stay higher for longer in a day than is ideal. These people are predisposed to hold on to fat, notably above the waist, rather than to mobilise it. The only solution for them, Taubes says, is keto. “Lean folks aren’t like us. They don’t get fat when they eat carbohydrates; they may not hunger for them just thinking about them. They have a choice to live with carbs or not. We don’t.”
Keto is not a short-term diet “fix”, but a way of eating for life. It keeps you in a metabolic state – ketosis – whereby your body stops using sugar for energy and starts to break down stored fats instead. The liver converts these fats to molecules known as ketones, which the body uses for energy. Taubes argues persuasively that people who are prone to the metabolic disorder of excess fat accumulation must embrace this approach even though it means the entire carbohydrate food group is off-limits. “It is that simple. Just like smokers who quit cigarettes and drinkers who abstain from alcohol, fixing the condition requires a lifetime of restriction” because they have to “remove the cause of the excess body fat from their diet”.
The idea that carbohydrate is fattening, dangerously so for some people, is not new. In 1825, the French gastronomy writer Brillat-Savarin, who spent 30 years struggling with his weight and called his paunch his “redoubtable enemy”, noted that in more than 500 conversations he had held with “dinner companions who were threatened or afflicted by obesity”, the foods they craved were breads, starches and puddings. He gave short shrift to those desperate to lose weight, but appalled by the idea of forsaking carbs for life: “Then eat these foods and get fat and stay fat!” Taubes is more diplomatic, but his underlying message is essentially the same.
The very notion that carbohydrate restriction is vital for some people is currently contentious. The UK government’s healthy eating script still tells us all to base our meals on starchy food and in some conventional public health circles, a diet that eliminates carbohydrates is considered potentially dangerous, a contention that Taubes does a good job of dispelling by referring to up-to-date nutritional science.
Adherents to the conventional low-fat gospel will splutter into their skimmed milk when Taubes points out that those who cut out carbs need to eat more fat and, in particular, “vintage fats”, including cold-pressed olive and coconut oil, and all animal fats, and to eschew modern fats, such as industrially refined “vegetable” oil and margarine. “Eating foods that humans have been eating for thousands, or hundreds of thousands of years, and in the form in which these foods were originally eaten, is likely to have fewer risks and so be more benign than eating foods that are relatively new to human diets or processed in a way that is relatively new.”
Taubes’s advice is directly at odds with the stale paradigm entrenched in public health circles for the last 60 years. But he is one of a growing band of medics and nutritional experts whose results show that dietary thinking should move on. Those who feel doomed to be fat would be well advised to digest every word of Taubes’s cogently argued, agenda-shifting book. It could be a life-changer for some.
• Joanna Blythman is an investigative journalist and author. Her most recent book is Swallow This: Serving Up the Food Industry’s Darkest Secrets (Harper Collins)
• The Case for Keto: The Truth About Low-Carb, High-Fat Eating by Gary Taubes is published by Granta Books (£14.99). To order a copy go to guardianbookshop.com. Delivery charges may apply