Here are two diets. The first one is a high-carb, low-fat diet; 15% from fat, I think, could be considered a true low-fat diet. The second has considerably less carb and over double the fat, but many studies still consider it low-fat, for example the famous PREDIMED (their low-fat control group was eating 37% fat).
Which diet do you think resulted in more weight loss and improved insulin sensitivity?
#1: 70% of calories from carbohydrate, 15% from protein, 15% from fat, 15 g fiber/1,000 kcal
#2: 50% of calories from carbohydrate, 16% from protein, 34% from fat, 6 g fiber/1,000 kcal
This study out of Joslin and Harvard says Diet #1 was better:
Improvement of Insulin Sensitivity by Isoenergy High Carbohydrate Traditional Asian Diet: A Randomized Controlled Pilot Feasibility Study, PLOS ONE, September 2014
It was well controlled; meals were delivered to participants in their homes. They don’t give details about the food besides that Diet #1 was modeled after a traditional Asian diet (TAD) and Diet #2 was modeled after a typical Western diet (TWD). Diet #1 was low in animal-based protein, Diet #2 contained protein mostly of animal origin. Protein (pure protein) and fat don’t contain fiber, so it’s easy to eat more fiber when you’re eating more carbohydrate.
The participants were Asian Americans and Caucasian Americans. Researchers wanted to see what would happen when someone at high risk of developing type 2 diabetes (Asians are thought to be at higher risk than Caucasians), eat not less carb, but more… a more traditional Asian diet.
Almost every marker they measured was improved in those eating the low-fat, high-carb Asian diet:
Weight (P<0.001), BMI (P<0.001), body fat (P<0.001) and trunk fat (P<0.001) were significantly reduced during TAD then increased during TWD.
Insulin AUC was significantly reduced after TAD (P = 0.001). Total cholesterol (P<0.001), HDL (P<0.001) and LDL (P<0.001) were significantly decreased during TAD while increased during TWD.
Consumption of TAD significantly decreased indications of systemic inflammatory markers.
One of the most striking effects of TAD was the significant improvement in insulin sensitivity (decreased insulin AUC), and improvement in glucose metabolism (decreased glucose AUC) observed among AA with high risk for diabetes.
If you read through the study, you’ll see they were trying to keep people from losing weight. People on the TAD lost weight anyway:
Interestingly, for the participants in the control group who stayed on the TAD throughout the entire study, an additional 119.8 kcal/day was provided during the second 8 weeks of TAD to maintain weight. With an extra 6,708 kcal over the last 8 weeks of the study, 0.9 kg weight increase would be expected, instead, weight loss of −0.4 kg was observed. This observation raises the possibility that consumption of TAD may facilitate weight loss.
Recent studies have suggested that high carbohydrate diets have contributed to the obesity epidemic and worsening of glucose metabolism. Our study shows that a high carbohydrate meal consisting of high fiber and low fat content reduces the risks of diabetes and cardiovascular disease in both AA and CA, and helps reduce weight and body fat.
People who show signs of diabetes are doing themselves a disservice by not trying a low-fat, high-carb diet. They are concerned their blood glucose will rise if they eat so much starch. That only happens when someone continues to eat lots of meat, cheese, and added fat. Olive oil is a fat.
Note George King‘s name in the author list.