Are Diets High In Carbohydrates Making You Fat? Part I

Are these to blame for your current waistline?
I wanted to cover a few examples of diets differing in carbohydrate composition on our body composition and bio markers of health. Part I will go over a few diets that are high in carbohydrates, and we’ll examine what these diets had on body composition and blood work. Part II will cover a few misconceptions that may be leading individuals to believe that carbohydrate are the evil carbohydrate that is causing the obesity epidemic. Is it even possible to be lean, or to even lose weight on a high carbohydrate diet? These questions will be answered.

Let’s first look at the Okinawan diet. This diet was composed of 85% carbohydrate, 9% protein and 6% fat. “Wow these people must be huuuuge,” you are thinking to yourself right? Well… Not so much. Residents of Okinawa: are known for their long average life expectancy, high numbers of centenarians, and accompanying low risk of age-associated diseases. (Bang) How can it be that a diet composed of an absolute crap load of carbohydrates produce some of the healthiest people on the planet!?!?

There is a multitude of possibilities that could contribute to their health. If you examine pretty much any diet, regardless of macronutrient composition, you will often observe an improvement in biomarkers of health (total cholesterol, triglyderides, blood insulin levels, blood glucose levels etc.). For instance, in an interesting study on how differing macronutrient ratios effects fat loss, the researchers got some interesting results. The diets differed in macronutrient composition, some were higher in carbohydrates, others lower in carbohydrates and higher in fat and/or protein etc.

Total cholesterol was reduced in all of the diets regardless of composition. This would lead you to assume that a reduction in total body weight may result in a reduction in cholesterol. Even the diets composed of 40% fats in this study resulted in a reduction in total cholesterol.

Let’s look at the results in fat loss for the different diets. There were no major differences in abdonminal fat, subcutaneous fat or visceral fat between all the diets. The diet with the largest composition of carbohydrates was 65% carbohydrate. The lowest was 35%. There was still no difference in fat loss between the diets with different carbohydrate ratios. Hmm.

Let’s look at the Hawaiian Diet. This diet is characterized by a high ratio of carbohydrate ~77%. The studies participants ate ad libitum for 21 days consuming the traditional cultural foods of Hawaii. The participants were encouraged to eat to satiety. After 21 days, participants lost an average of 10.8 pounds on this diet. What effects did this diet have on biomarkers of health you ask?

Blood pressure decreased from an average of 136.0/82.7 mm Hg to 125.5/78.9 mm Hg. Average lipids decreased simultaneously with total cholesterol (205.3 to 156.9 mg/dl). LDL decreased from 125.9 to 94.9 mg/dl, HDL also decreased HDL from 38.3 to 31.3 mg/dl. No we don’t really want ta decrease in HDL, but high carbohydrate diets aren’t conducive to raising HDL. Triglycerides decreased from 238.7 to 152.2 mg/dl. The Cholesterol:HDL ratio decreased from 5.8 to 5.2 (the cholesterol:HDL ratio is one of the most accurate measuring tools for predicting a coronary event). Oh yea, did I mention that blood glucose levels dropped from 112.2 to 91.5 mg/dL?

There are numerous other examples of high carb diets, not only working successfully in clinical trials to help lose weight, but they also have shown to improve certain biomarkers of health. I’ll give you one more, just realize there are many, many more to draw from. Alford BB et al examined diets differing in carbohydrates and protein on obese women. The high carb diet contained 75% carbohydrate, the low carbohydrate diet contained around 25% carbohydrate. There was also a medium carbohydrate diet that was composed of 45% carbohydrate. All three diets were kept at a total of 1200 calories over a 10 week time period. After the 10 weeks there were no significant differences in weight and body fat.

If improving biomarkers of health are important the research shows that diets high in carbohydrates won’t necessarily hinder improvements. However, I’ve used pretty extreme examples in this blog post to illustrate my purpose. A diet lower in carbohydrates (40-45%) will tend to increase HDL, decrease tryglycerides, improve fasting insulin and blood sugar levels, and decrease fatty acid levels. Just realize that a diet higher in carbohydrates may have the same effects, just to a lesser degree. The total reduction in calories will results in an improved blood profile for many individuals!

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