We recently discovered a US nutrition textbook from 1999. This book has a good claim to represent the orthodoxy. It contains the views of multiple experts in the various areas of nutrition.
By far the bulk of the book is sound nutrition science, and still worth learning – but there are areas where it wanders away from science fact and stakes a position that seems questionable today.
It’s the section on Energy Balance and Weight Control that’s the real eye opener.
It’s very much about calories in vs calories out. Well, of course it is, but with the 1999 diet plan, food intake and activity level need to be focused on to a high degree.
The reason given for preferring a high-carbohydrate diet is slightly gob-smacking today; because carbohydrate stimulates energy expenditure. This is the old metabolic advantage argument sometimes used by both sides of the carb vs fat debate..
The following are listed among “practices that can stimulate metabolism while dieting”.
- “- Fidget when sitting and standing [Seriously? This seems pretty desperate! Try telling a person who fidgets NOT to fidget, and you’ll see how practical this advice is.]
- – Eat breakfast, so food intake is spread throughout the day. Each time food is consumed, metabolism increases
- – Follow a carbohydrate-rich diet; much of this is further processed by the liver, which uses energy.”
We know that the low-fat diet will produce weight loss in people who are satisfied enough by it, or have enough willpower, to restrict calories.
The problem is, what happens to people who become hungrier on such a diet, and what happens when such Food Pyramid diet advice is applied to the whole population without calorie restriction, and in the presence of sweet treat foods, in the belief that this will also help with energy balance and weight control? The frequent high-carbohydrate meals stimulate high insulin levels, and the processing of carbohydrate by the liver results in increased ectopic fat and insulin resistance, tending to promote increased fat storage and appetite and higher blood sugars.
Further, some forms of calorie restriction can produce a lasting drop in the metabolic rate, which then makes it hard to avoid regaining weight. This is why the low-fat diet plan has you eating all the time, losing weight slowly (if at all), and trying to fidget; to keep up the metabolism. But low carb diets, and plain fasting, don’t depress the metabolic rate. They don’t set you up to fail as the Biggest Loser diet, which is Eat Less, Move More taken to its (il)logical extreme, does. This is explained very neatly by Jason Fung in a recent post at Diet Doctor, using the evidence from 3 recent metabolic studies by Kevin Hall.
This is the real “metabolic advantage” of LCHF – not a boost to metabolism as once thought, but its protection.
The problem with the 1999 advice is not the low—fat diet as such, but the lack of respect for and serious scientific consideration of alternative ways of eating, which is explicable here by the predominating fear of animal fat and cholesterol, and the higher calorie-per-gram value of fats. The existence of an officially-sanctioned Food Guide Pyramid must also have tied the hands of textbook writers – if they presented a convincing case for an alternative, what publisher would take a risk on their work? Perspectives In Nutrition gives several pages for experts to debate, sometimes hotly, divergent views on undecided topical issues such as the use of vitamin E supplements, but fails to provide the diversity of expert opinion about weight control that surely (?) still existed in 1999. The failure to consider the role of insulin in the energy balance response to diet, and to look into the contradictions and controversies around diet, cholesterol and health, undermines all the good science and good intentions in this book and results in the building of a massive structure of difficult-to-follow advice on a shaky foundation. A whole generation of today’s nutritionists and dietitians were given no reasons to think that carbohydrate restriction might be a safe and useful strategy, and were, it seems, trained to dismiss it out of hand as a ‘fad diet’.
The one-size-fits-all low fat, high carbohydrate diet plan, which has now been shown to be, on average, less effective than just about anything else you could try, really did preside over nutrition teaching during the obesity epidemic, however much this might be denied today.
It is a relief to turn from the Energy Balance section of Perspectives in Nutrition to the sound sense of John Yudkin, writing in 1963.
A Cruel Kindness 1967
People were not told to restrict fat or animal fats in the 1960’s. (The subjects in Yudkin’s studies ate about 100 grams of fat a day, both before and after restricting carbohydrate). Once animal fat in the diet was reduced by public decree, and carbohydrate intake increased, the numbers of those who were overweight increased. By 1999 the problem was recognised and great intellectual effort went into proposing solutions, but the simplest classical solution was overlooked, perhaps because the problem in 1999 seemed much more complex than it had in 1963 (or in 1825, when Brillat-Savarin first introduced the idea of the “fattening carbohydrate”), thanks in no small measure to Ancel Keys and the diet-heart hypothesis.
It became a case where “The weakness of the remedy lies in its simplicity”. The growth of the academic nutrition establishment after Ancel Keys’ huge success, and the need to keep that workforce employed, meant that arguments as simple as Yudkin’s became unwelcome, even if their basic truth could be demonstrated. In 1999, simple propositions were what defined quacks and fad diets. Yet complex instructions have a limited utility to the general public.
Surely, rather than always glamourising the complexity of science and the “multifactoral” nature of disease, it is a better approach to some public health problems to find the most true of the simple propositions, and make sure everyone knows them?