Added Sugars

From Aaron Carroll:

As we talk about how hard it is to combat obesity, it’s worth thinking about numbers like this once in a while. If we could get kids to give up half, not even all, of the added sugar in their diet, their overall calorie consumption would drop by 8%. They’d be dropping about 140-180 calories a day from their diet. And those calories are totally empty – they’re from added sugars they don’t need, and that won’t satiate them. When other research shows that reducing your caloric intake by 20 (yes, twenty) calories per day for three years could lead to an average weight loss of 2 pounds, making this small change could be a big deal.

Okay, there is a good point here and a really bad point here.  The good point is that added sugar seems to be a bad thing.  It promotes tooth decay (with 2 root canals, I can say that this is a big deal), it seems to be efficiently absorbed, it is associated with diabetes (a disease you really do not want), and it's nutrient value is null.

But the idea that a 20 calorie a day change will mechanically lead to a 2 pound weight loss in 3 years is kind of odd.  I mean it works, mathematically.  But it ignores all sorts of issues: like how does the body adapt to less intake, what foods are eaten (is it the same composition with portions shrunk by 1%?), and how this may alter activity levels.  The claim makes something that we know is hard sound very, very easy.

Programs like Weight Watchers seem to partially get good results by restriction, but they also seem to have incentives to change the composition of the diet.  Just look at how fruits and vegetables can be zero points in the current diet.

So, in an odd sort of way, the last point detracts from the main issue here: added sugars are bad and trying to expose your children to less of them is unlikely to be a bad thing.

A classic natural experiment

This post was requested by Mark.

One interesting natural experiment in diet and exercise was rationing in wartime Britain where the population ate less and exercised more (petrol was also rationed). The results were fairly impressive:

As a result of the balanced diet provided by rationing, children's health improved and on average they were taller and heavier than before the war.

The incidence of anaemia and tooth decay dropped - while the average age at which people died from natural causes increased, despite the stresses and strains of war.

The principles behind rationing sound surprisingly similar to today's health messages: reduced consumption of meat, fats and sugar and more of the sort of foods, such as vegetables, which provide essential vitamins and minerals.

this led to other health benefits:

A war-time regiment would also help reduce your risk of heart disease, Type 2 diabetes and high blood pressure, as well as cancers such as post-menopausal breast cancer, kidney and colon cancer.

The same outcome of rationing was seen in Australia:

The government feared that rationing would result in deterioration in health on the home front but, in fact, the outcome was positive. Rationing resulted in a decline in diet related problems like obesity, diabetes and heart disease.

So it is clear, that whether or not the wartime Commonwealth diet was optimal, there is a known population-level intervention that will result in better health outcomes: restriction of food.

Now, as a matter of public policy, I am clearly opposed to doing this in a coercive manner (but then I still see tobacco smoking as a personal choice). But it is clear that relatively simple diets can have surprisingly positive health benefits.