I was reading an article by Zoe Harcombe this morning where she covers why we eat carbohydrates. In the article she gives the year in which the United States started issuing dietary guidelines. It’s 1977 by the way. I had always thought the federal government’s involvement in the public school system, in particular the school lunch program, contributed to the rapid rise in childhood obesity. I found a chart on the CDC’s web site that tracks with the issuing of federal dietary guidelines.
When dietary guidelines were introduced in the US in 1977 and the UK in 1983, telling people to eat no more than 30% of their calories in the form of fat, this inevitably meant that people were being told to consume at least 55% of their calories in the form of carbohydrate. For the avoidance of doubt, the implication of setting a cap on fat was spelled out: “Increase carbohydrate consumption to account for 55 to 60% of calorie intake” (Ref 7).
The main reason we eat carbohydrates today, therefore, is because we were told to avoid fat. It was not because we had studied carbohydrates and found them to be optimally healthy at an intake of 55%. We had not even studied carbohydrates to know that they were safe at an intake of 55%. I can’t emphasise this point strongly enough. Our intake of carbohydrate is the consequence of demonising fat. However, official dietary advice doesn’t give this as the reason for eating carbs, as it hasn’t made this connection (Ref 8). Documents such as the Dietary Guidelines for Americans and the UK Eatwell Guide focus on telling you to eat carbohydrates rather than explaining why.Why we eat carbohydrates – Zoe Harcombe
In the chart you can clearly see from 1963 to about 1977 childhood obesity rates were relatively flat. Starting somewhere between 1976 and 1980 the rates increase dramatically. From around 5% in 1963 to 15% to over 20% by 2016. Is it just a coincidence that US dietary guidelines started at the same time the obesity rate skyrocketed? Correlation is not causation but this looks like pretty strong evidence to me.