Saturated fat is only bad when carbs are overconsumed

The cornerstone of our nation’s dietary guidelines for the last 40 years has been to reduce dietary fat, especially saturated fat. How have the dietary guidelines performed?

Since their creation, the incidence of obesity and diabetes has skyrocketed and the trajectory continues upward. Currently, two-in-three adults in the U.S. are overweight, one-third are obese, ~25 million have diabetes, and more than 60 million have metabolic syndrome (i.e., pre-diabetes). Childhood obesity and diabetes diagnoses have tripled. In my opinion, the guidelines have failed. 

Part of the problem is that as people tried to decrease saturated fat, they replaced those calories with an even greater amount of carbohydrate, especially sugars and refined starches. Researchers also have critically examined the premise that saturated fat is harmful. Multiple meta-analyses performed in the last 5 years have all come to the same conclusion—dietary saturated fat is not associated with an increased risk of obesity or disease.

However, the accumulation of saturated fat in the blood and tissues is consistently related to an increased risk of obesity, diabetes and heart disease. Why is there an apparent contradiction here? My laboratory group has now published 3 studies that all show it is the overconsumption of carbohydrate that drives up levels of saturated fat in the body.

The bottom line is that an unintended consequence of encouraging Americans to decrease saturated fat is that many people over-consumed carbohydrate, which manifested itself in an epidemic of obesity and diabetes. Studies also show that low-fat diets (20-30% of calories) are associated with lower testosterone levels compared to diets higher in fat (40% of calories). We would all be better off focusing on reducing our intake of sugars and starches and easing back on our unnecessary fear of saturated fat.   

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