The right diet is the key to managing many diseases and to improving general quality of life. For this condition, scientific research has found benefit in the following healthy eating tips.
- Although more research is needed, diets high in protein may benefit people with IRS.
Very little research has investigated the effect of increasing dietary protein intake on insulin resistance in people with or without IRS. One controlled study found that people with some features of IRS lost more weight on a high protein diet than on a high-carbohydrate diet, although both diets produced similar improvements in a measurement of insulin sensitivity.30 Preliminary and controlled trials in people without IRS have also shown that substituting protein for carbohydrate in a low-fat diet can improve blood lipids (cholesterol, triglycerides and HDL) towards reduced heart disease risk.31,32 More research is needed on the effects of high protein diets in people with IRS.
- Choosing carbohydrates with a low glycemic index (foods that don’t cause a spike in blood sugar) and foods that are high in fiber may improve insulin sensitivity.
High-carbohydrate diets have also been shown to improve insulin sensitivity; the reason for this may partly be that weight loss often occurs on this type of diet,33 or that these diets are low in fats, such as saturated fat, that worsen insulin sensitivity.34,35 The type of carbohydrate consumed may influence the effect of a high-carbohydrate diet on insulin sensitivity. Animal research suggests that very high intake of fructose or sucrose worsens insulin sensitivity, but human studies have been inconsistent.36,37 “Glycemic index” refers to the blood sugar-raising effect of a food, and there is preliminary evidence from some,38,39,40 though not all,41 human research, that consumption of low glycemic index foods improves insulin sensitivity. Effects on glycemic index may be one reason dietary fiber is associated with better insulin sensitivity.42 As with dietary fat intake, it makes sense for people with IRS to choose carbohydrates according to their effects on heart disease risk. Therefore a diet low in refined carbohydrates and high in fiber appears most prudent.43
- Avoiding fats from meat, dairy, and processed foods high in hydrogenated oils while allowing fish, olive oil and other monounsaturated fat sources makes sense for people with IRS.
The effect of dietary fat on insulin resistance seems to depend on the type of fat eaten. Preliminary studies in animals and humans suggest that insulin resistance is worsened with increased use of saturated fat and improved with increased unsaturated omega-3 fatty acids from fish, while the role of other unsaturated fats is less clear.44 However, recent research has reported that diets high in monounsaturated fat improve insulin sensitivity in both healthy people and people with diabetes.45 A diet low in saturated fat, but which allows both fish and monounsaturated fat makes sense for people with IRS, because such a diet is associated with protection from heart disease. Recently, a low-fat diet allowing fish was shown to decrease insulin resistance in people with IRS.46
In two controlled studies,47,46 a combined program of a weight-loss diet lower in fat and higher in fish, along with exercise three times per week, improved several measures of insulin resistance, blood triglycerides and cholesterol, and blood pressure in a group of people with IRS.
- In one study, a diet low in fried foods and sausages and high in vegetables, fruits, fish, and complex carbohydrates such as whole grains was shown to protect against many aspects of IRS.
Some authorities recommend people with IRS avoid high-carbohydrate diets, and some recommend a diet lower in carbohydrate than current public health guidelines suggest. The rationale is that high carbohydrate intake stimulates increased insulin levels, which can lead to high triglycerides, low HDL, and other adverse changes in the levels of blood fats that contribute to heart disease risk.48 Other authorities disagree, however, because they believe a lower carbohydrate diet will result in higher calorie intake from fat, leading to more difficulties with overweight, insulin resistance, and heart disease risk.49 A recent preliminary study suggested that a healthy, balanced diet low in fried foods and sausages, and high in vegetables, fruits, fish, and complex carbohydrates, such as whole grain rice and pasta, was associated with protection from many aspects of IRS.50