Insulin Resistance: Part Four
Reclaiming Your Power
The purpose of this fourth and final part of the insulin resistance series has two goals: to inform you and to empower you. To show you that you can take control of your health destiny when it comes to diabetes and blood sugar management. That it is in your hands or, more specifically, on your plate. In Part One, we unpacked what insulin is, in Part Two, we broke down insulin resistance, and in Part Three we highlighted the main nutrients and foods of concern. Now, insulin resistance is a total body condition and, with that, there are total body ways to address it. These include exercise, sleep and stress management. But today, we will hone in on what dietary intervention studies have shown us about managing, and even reversing disease. We’ll be spanning forty years of research, but it actually goes back over a hundred years! Let’s get started.
Moving Away From a Western Diet
In the previous blog, we looked at how saturated fat is particularly problematic for insulin resistance. Foods high in saturated fat are meat (especially red meat), dairy (especially high fat processed dairy foods like cheese), and coconut and palm oils. We also looked at how refined carbohydrates negatively impact insulin resistance and blood sugar management. Refined carbohydrates include juices, soft drink, sweets, and white flour products. A combination of these foods very much reflects a typical Western dietary pattern.
Vegetarian whole food diets have received much interest in their ability to manage diabetes and blood sugar, as they are naturally low in saturated fat and refined carbohydrates, and high in foods known to confer blood sugar benefits (1). Observational data of vegetarian populations including Seventh-Day Adventists and Buddhists have shown dramatically reduced diabetes risk of around 50% (1). However, we need more rigorous science to really understand whether these relationships are causative. Let’s take a look at three studies.
Two Diets Put to the Test
A 2009 study by Barnard et al compared a low-fat vegan diet to the 2003 American Diabetes Association diet, in a randomised control trial over 74 weeks (2). The low-fat vegan group (N=49) omitted animal foods, fatty foods, and high glycaemic foods, and based their diet around vegetables, fruits, grains and legumes. They were not told to restrict their food intake at all, nor count carbohydrates. The conventional diabetes diet (N=50) was based on nutrients rather than foods. The nutrient break down was 15-20% protein, <7% saturated fat, and 60-70% carbohydrate and monounsaturated fats. For overweight participants (forty seven out of fifty), an energy intake deficit of 500-1000 calories per day was prescribed. Here’s what they found at 74 weeks:
- Both groups experienced significant average weight loss, 4.4 kg for vegans and 3.0 kg for conventional. When limited to adherent participants, mean weight loss improved to 6.8 kg and 4.9 kg.
- Reductions in HbA1c, a marker of blood sugar control over 3-4 months, was 0.34 for the vegan group and 0.14 for the conventional group. Better blood glucose management for type 2 diabetics is indicated by lower HbA1c. So the vegans performed better here.
- Diabetic medications were reduced by 20% in the vegan group and 10% in the conventional group
Keep in mind, the conventional group was utilising calorie restriction to help achieve these results, whereas the vegan group were able to eat as much as they wanted. But this presents a question: what if the benefits of a vegan diet are just because of weight loss? Luckily, the next study will shed some light on this.
Weight Loss vs Diet
A metabolic ward study in 1979 sought to determine whether a high carbohydrate, high fibre, low fat diet could improve insulin functioning in twenty normal-weight men who had type 2 diabetes with insulin-dependence (3). Most patients began using insulin shortly after their diagnosis. This meant that they were insulin resistant and couldn’t produce enough insulin to manage their blood sugar levels. We discussed this more in Part Two. A metabolic ward study is carried out in a hospital, and researchers have full control over what subjects eat.
Firstly, the participants were placed on a control diet for about a week, which was similar to the supported diabetic diet at the time. This diet was 20% protein, 43% carbohydrate, and 37% fat, and contained 26 g of fibre. This is very much representative of a standard Western diet. The experimental high carbohydrate and fibre (HCF) diet on the other hand was 21% protein, 70% carbohydrate, only 9% fat, and included 65 g of fibre. Of note is that saturated fat decreased by 80% and cholesterol by 86% in the high fibre diet. There was literally 100x more fibre consumed on this diet than cholesterol. Since fibre is only found in plants and cholesterol is only found in animal foods, this was a plant-based diet.
Further, the diets were designed to be weight maintaining. The men were not allowed to lose any weight, and often complained about being very uncomfortable from being so full. So, what did they find? After an average of 16 days on the plant-based HCF diet the average daily insulin dose reduced from 26 to 11 units. Fasting and post-meal glucose were lower on the HCF diet, even though less insulin was being used and more carbohydrates consumed. Insulin therapy was discontinued in nine subjects, who were previously taking between 15 and 32 units daily. Average serum cholesterol also dropped from 206 mg/dl to 147 mg/dl. All this within an average of sixteen days.
Let’s look at one of the patients:
- A 57 year old man …
- Had diabetes for 9 years …
- Used 18 units of insulin on the control diet …
- Insulin used after 21 days of HCF diet … zero
- Fasting glucose control diet: 239 mg/dl … WITH INSULIN
- Fasting glucose after 21 days HCF diet: 155 mg/dl … WITHOUT INSULIN
A Holistic Online Coaching Program
A 2019 study by Sarver and colleagues evaluated the effectiveness of an online diabetes coaching service, Mastering Diabetes, in a pilot study (4). The Mastering Diabetes method involves a low-fat high-carbohydrate plant-based diet, based on fruits, vegetables, legumes, and whole grains. Refined carbohydrates and animal foods are omitted and plant fats reduced. They support people to implement this diet as well as lifestyle adjustments (including exercise, intermittent fasting, and stress management) to optimise blood sugar control.
103 participants with type 2 diabetes completed a survey outlining their experience over six months to one year. For reference, diabetic HbA1c range is >6.4%. Prior to the program, the participants’ mean starting HbA1c was 8.63 and the mean ending value was 6.60. This 2.03 point reduction was a 30.76% decline, which is a highly significant improvement. HbA1c, by comparison, in the first cited study only declined by 0.34 in the vegan group and 0.14 in the conventional diabetes diet over almost 1.5 years. Even more impressively …
combined pharmaceutical therapy for type 2 diabetics, including the use of Metformin,
lowered HbA1c by only 1.5 over 2 years (5).
Clearly, the Mastering Diabetes method is highly effective in improving blood glucose control, and their approach is contrary to many mainstream low-carbohydrate regimens currently encouraged and prescribed.
Key Take Aways
The science suggests that a dietary pattern that is low in saturated fats, trans fats, animal products and refined carbohydrates is best for reducing insulin resistance, increasing insulin sensitivity, improving insulin production, and managing diabetes. Swapping saturated fat for polyunsaturated fat foods is also helpful. A diet that is high in whole plant foods is key and pivotal not only to help manage symptoms, but to help resolve the disease process and to reduce risk of chronic disease long-term. For clarity, I have listed the foods that fall under these nutritional categories below.
Avoid or significantly limit:
Saturated Fat: meat (especially red & processed meat), dairy (especially full-fat), coconut oil, palm oil, & cocoa butter (e.g. chocolate).
Animal Products: meat, dairy, eggs, & seafood.
Trans Fat: margarines, processed food (especially containing partially hydrogenated vegetable oils), and animal foods.
Refined Carbohydrates: soft drinks, sweets, flour, breads, pastas, white rice, puffed grains, cakes and fruit juices.
Food Foundations:
Whole Plant Foods: Fruits, vegetables, legumes, & intact whole grains.
Modest amounts of whole polyunsaturated fat-rich foods: especially flax seeds, chia seeds, hemp seeds, walnuts - but not their oils which lack fibre and many micronutrients while contributing more to weight gain.
If you would like guidance on how to better manage your blood sugar and related metabolic conditions, I am available for nutrition and lifestyle consultations. Please see here for more information on nutrition services.
Written by Jessica Zabow
Accredited Practicing Nutritionist (BHSc)
& Yoga Teacher (RYT500)
References
Olfert, M.D., & Wattick, R.A. (2018). Vegetarian diets and the risk of diabetes. Current Diabetes Reports, 18(11), 1-6. https://doi.org/10.1007/s11892-018-1070-9
Barnard, N.D., Cohen, J., Jenkins, D.J.A., Turner-McGrievy, G., Gloede, L., Green, A., & Ferdowsian, H. (2009). A low-fat vegan diet and a conventional diabetes diet in the treatment of type 2 diabetes: A randomized, controlled, 74-wk clinical trial. American Journal of Clinical Nutrition, 89(1), 1588S-1596S. https://doi.org/10.3945/ajcn.2009.26736H
Anderson, J.W., & Ward, K. (1979). High-carbohydrate, high-fiber diets for insulin-treated men with diabetes mellitus. The American Journal of Clinical Nutrition, 32(11), 2312-2321. https://doi.org/10.1093/ajcn/32.11.2312
Sarver, J., Khambatta, C., Barbaro, R., Chavan, B., & Drozek, D. (2019). Retrospective evaluation of an online diabetes health coaching program: A pilot study. American Journal of Lifestyle Medicine, 15(4), 466-474. https://doi.org/10.1177/1559827619879106
Gerich, J., Raskin, P., Jean-Louis, L., Purkayastha, D., & Baron, M.A. (2005). PRESERVE-beta: Two-year efficacy and safety of initial combination therapy with Nateglinide or Glyburide plus Metformin. Diabetes Care, 28(9), 2093-2099. https://doi.org/10.2337/diacare.28.9.2093