Diet Can Improve Your Insulin Sensitivity

The development of type 2 diabetes, metabolic syndrome, heart disease, fatty liver, and other unpleasant disorders can come from insulin resistance. Insulin resistance puts a strain on the hormone insulin’s ability to allow glucose, the most basic form of energy, from entering the body’s cells. The lack of energy to our body can be physically detrimental. It is well known that we can reverse the effects of insulin sensitivity through calorie restriction, exercise, and weight loss.^1,2 A group of researchers led by Meghana Gadgil, MD, MPH who worked on the OmniHard Trial published the study “The Effects of Carbohydrate, Unsaturated Fat, and Protein Intake on Measures of Insulin Sensitivity Results from the OmniHeart Trial.” They were interested in understanding if the macronutrient (carbohydrate, fat, and protein) composition of a diet could change the level of insulin sensitivity to benefit the body.¹

There were 160 participants which completed the study. Participants had a mean age of 54 years, and had prehypertension or stage 1 hypertension. The study was a three-period crossover feeding study.¹ Participants were randomly broken into three groups; a carbohydrate-rich diet, protein-rich diet, and fat-rich diet. Diets were administered to patients. The group that had a carbohydrate-rich diet had a diet that was similar to the Dietary Approach to Stop Hypertension diet. The carbohydrate-rich diet’s energy composition was 58% from carbohydrates, 15% from protein, and 27% from fat. The protein-rich diet’s energy composition was 25% from protein, 48% from carbohydrates, and 27% from fat. The fat-rich diet was similar to the Mediterranean diet and was high in saturated fat. The energy composition was 37% from saturated fat, 48% from carbohydrates, and 15% from protein.¹ Even though this diet was similar to the Mediterranean diet it must be taken into consideration that there are a variety of diet styles within the Mediterranean diet.³ The participants’ insulin sensitivity was measured by “the quantitative insulin sensitivity check index (QUICKI)”. QUICKI measures fasting glucose and insulin levels in the blood. The group that had a higher intake from saturated fat ended up significantly increasing their insulin sensitivity. The baseline QUICKI score was .35 which increased by .005 for the saturated fat-rich diet, this is both statistically and clinically significant.¹

This was a very good study because they controlled the known factors of improving insulin sensitivity such as weight loss, calorie restriction, and exercise.^{1, 2} Weight of participants was kept stable throughout the study. The study was a three-period crossover feeding; the participants were all given a chance to consume all three of the different diets. In between diets the participants had a 2-4 week washout period where they were able to eat what they usually eat so they could get the best results possible from the introduced diets.¹ One of the weaknesses of this study was that they were very exclusive in whom they allowed to participate in the study. Participants had to have prehypertension or hypertension stage 1 to participate in the study. Participants were excluded if they had a prior cardiovascular disease, preexisting diabetes, LDL cholesterol above 220 mg/dL, fasting triglycerides greater than750 mg/dL, or a weight of over 350 pounds. Some medications disqualified participants from participating such as insulin hypoglycemic agents, medications that affect blood pressure or lipid levels, and vitamin or mineral supplements. Consumption of more than 14 alcoholic drinks per week wasn’t accepted.¹

Consuming a saturated fat-rich diet similar to the Mediterranean diet will have a profound effect on insulin sensitivity. When consuming this diet it is important to take into consideration the different ways foods are processed, prepared, and produced in other areas of the world. Food preparation and products may be different in America than they are in the Mediterranean area.³ Another study published in The New England Journal of Medicine titled “Primary Prevention of Cardiovascular Disease with the Mediterranean Diet” found that a Mediterranean diet supplemented with olive oil or nuts will reduce the risk of cardiovascular disease.⁴ This is significant because not only will the Mediterranean diet help reduce insulin sensitivity in those with prehypertension or hypertension stage 1, but help reduce the risk of major cardiovascular issues.^1,4 Changing a lifestyle to incorporate new eating habits can be difficult but is obtainable. For some individuals to improve insulin sensitivity it may be easier to exercise, restrict calories, and/or lose weight.^{2, 5}

If calorie restriction, any weight loss, or exercise is too difficult for someone who has insulin resistance they are able to modify their diet to increase their insulin sensitivity. The saturated fat rich diet similar to the Mediterranean diet, 37% saturated fat, 48% carbohydrates, and 15% protein, would be a good alternative. The elevated saturated fats were mainly from oil sources such as olive, safflower, or canola oil.¹ The benefits from this type of diet will not only improve insulin sensitivity but help reduce the risk of cardiovascular disease as well.^1,4  Although it hasn’t been studied, weight loss, calorie restriction, exercise, and a diet rich in saturated fat may have a synergistic effect to improving insulin sensitivity.

References

1. Gadgil M, Appel L, Yeung E, Anderson C, Sacks F, Miller III E. The Effects of Carbohydrate, Unsaturated Fat, and Protein Intake on Measures of Insulin Sensitivity. Diabetes Care [serial online]. May 2013;36(5):1132-1137. Available from: Academic Search Premier, Ipswich, MA. Accessed February 4, 2015.
2. Ryan A, Katzel L, Prior S, McLenithan J, Goldberg A, Ortmeyer H. Aerobic Exercise Plus Weight Loss Improves Insulin Sensitivity and Increases Skeletal Muscle Glycogen Synthase Activity in Older Men. Journals Of Gerontology Series A: Biological Sciences & Medical Sciences [serial online]. July 2014;69(7):790-798. Available from: Academic Search Premier, Ipswich, MA. Accessed February 4, 2015.
3. Hoffman R, Gerber M. Evaluating and adapting the Mediterranean diet for non- Mediterranean populations: A critical appraisal. Nutrition Reviews [serial online]. September 2013;71(9):573-584. Available from: Academic Search Premier, Ipswich, MA. Accessed February 4, 2015.
4. Estruch R, Ros E, Salas-Salvado J, Covas MI, Corella D, Aros F, Gomez-Garcia E, Ruiz Gutierrez L, Fiol M, Lapetra J, Lamuela-Raventos RM, Serra-Majem L, Pinto X, Basora J, Munoz MA, Sorli JV, Martinez JA, Martinez-Gonzalez MA. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet. The New England Journal of Medicine April 4, 2013;368:1279-1290.
5. Golubović M, Dimić D, Antić S, Radenković S, Djindjić B, Jovanović M. Relationship of adipokine to insulin sensitivity and glycemic regulation in obese women — the effect of body weight reduction by caloric restriction. Vojnosanitetski Pregled: Military Medical & Pharmaceutical Journal Of Serbia & Montenegro [serial online]. March 2013;70(3):284-291. Available from: Academic Search Premier, Ipswich, MA. Accessed February 5, 2015.

Reviewed by Viktoriya Wolff