We Get Fat Because of Carbs
As you can see from the graphs, our carb intake has fluctuated up and down, while our fat consumption has gone up a bit. Some people say we became obese because of the low-fat recommendations, but people haven’t even largely been keeping to these guidelines, as the graph shows.
We’ve been eating the same amount of carbs at the beginning of the 1900’s as we were in the early 2000’s according to the graph, yet our obesity rate has sky-rocketed.
Looking to the Japanese, they eat a relatively high carb diet. As a percentage of calories, they eat 58% of their calories from carbs and we eat 49% (R). 58% is quite high. One study that I discuss below uses a high carb diet to mean 46% of calories are from carbs (R).
We actually decreased our carb intake by 4% from 1995-1997 to 2005-2007, yet our obesity rates still markedly increased over that period (R).
The Japanese eat 29% of their calories as fat, while we eat 38% (R). We eat roughly the same percentage of protein (R).
A recent study has found that a low-carb diet is more effective than a low-fat diet for weight loss (R), although both groups lost weight. What many don’t realize about the study is that both the “low-fat” and low-carb groups reduced their fat and calorie intake, so this refutes the popular claim that eating more fat leads to weight loss or that calories don’t matter (R).
In 2008, a high-quality study lasting 2 years was published by the New England Journal of Medicine that compared a low-carb diet, a low-fat diet, and a Mediterranean diet. The mean weight loss was 2.9 kg (6.4 pounds) for the low-fat group, 4.4 kg (9.7 pounds) for the Mediterranean-diet group, and 4.7 kg (10.3 pounds) for the low-carbohydrate group, demonstrating that the Mediterranean diet is equally as effective for weight reduction as a low carb diet. (R) The Mediterranean diet had a significant amount of carbs (45% vs 28%) (R), yet the weight loss was the same. This was the case even though the low-carb diet had 8% more protein (25% vs 33%), and protein is established to inhibit appetite. (I’ve created a modified Mediterranean diet template for people to build off of.) See the results below:
Looking at the totality of changes in health markers, I’d say the Mediterranean diet wins out, even though the low-carb dieters consumed fewer calories (Mediterranean diet had lower fasting glucose and insulin resistance) (R).
There were 2 studies done looking at weight loss differences between a high carb diet and a low carb diet when people were instructed to eat the same amount of calories (an isocaloric diet). There were no statistically significant differences between the diets. (R, R2)
I should mention, though, that in both studies the low-carb group lost more weight than the low-fat group, even though the results weren’t statistically significant. The low carbs lost 4 pounds more in the 6 months study and ~7 pounds more in the 12-month study. However, people on the low fat/high carb diets still lost 22.3 pounds and 25.3 pounds in the 6 and 12-month study, respectively. (R)
A variety of health markers were similar for both diets, but they tended to be a be a bit better for the high carb diet, though they weren’t statistically significant. The high carb diets had better LDL numbers and the low carb diets had better HDL numbers.
The nonstatistical difference in weight between the diets in the referenced studies can be more than explained by the fact that this wasn’t a controlled environment and these people prepared their own food.
What these studies tell me is that you can lose weight with any diet, even when you relatively up your carb intake, as the low fat diets do. Also, we should ditch low fat diets for weight loss.
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