Sometimes we could be forgiven for thinking that medical advice changes with the weather. Or with what's expedient for politicians at the time. Cynical? Moi??
Well, according to a new study from the US National Institutes of Health, it seems that cutting out carbohydrates helps us lose weight, but reducing fat is better for our health.
Scientists monitored every scrap of food eaten, every breath, and all exercise taken by people on controlled diets.
Carb reduction resulted in weight loss when calorie intake was cut, but people lost more weight when they reduced their intake of fat.
Obesity experts hope the news will stop people feeling guilty if they eat potatoes and bread in the mistaken belief that they are particularly fattening. While we only look at losing weight, we forget that the key to our health is the amount of fat we carry around with us. A sensible quantity of carbs is fine.
Dr Kevin Hall, from the National Institute of Diabetes and Digestive and Kidney Diseases said: "We did not investigate whether one diet would be easier to stick to over another, but this is likely to be a more important factor for people with obesity attempting to lose body fat in the real world."
Professor of diet and population health at Oxford University, Susan Jebb, said: "The real challenge for science is not the nutritional composition of the diet, but the behavioural strategies to promote adherence. All diets 'work' if you stick to an eating plan that cuts calories, whether from fat or carbohydrate, but sticking to a diet is easier said than done, especially given the prolonged time it takes to lose weight."
So what is the most effective diet? Susan Jebb's answer is simple: the one you can stick to!