If you’ve been diagnosed with type 2 diabetes, prediabetes or insulin resistance, you may have discovered that there’s a lot of competing, outdated, or just plain dubious advice out there about how and what you should eat. We’ve rounded up the latest science to help you understand the best options for your health.
What is Type 2 Diabetes?
In the United States alone, 11% of adults now have type 2 diabetes – and a further 38% have prediabetes.[*] Type 2 diabetes can lead to cardiovascular disease, kidney failure, blindness, limb amputations and cognitive decline. It is now also the 7th leading cause of death in the US.[*]
Although people think of diabetes as a blood sugar issue, it’s actually a problem with a hormone called insulin. Insulin is like a key that allows your cells to take in sugar (known as glucose) to make energy. Think of each cell in your body as a tiny club, with insulin as the bouncer – before a cell can access glucose, it needs insulin to lift the rope and let it in.
In type 1 diabetes, an autoimmune response or a virus destroys your body’s ability to make insulin. Without insulin, you can’t get glucose out of your blood and into your cells. In type 2 diabetes, your body loses sensitivity to insulin over time. Your pancreas has to pump out more and more insulin to get glucose into your cells, a state known as “insulin resistance” – until eventually, it gets to a point where it can’t produce enough to keep your blood sugar within a normal range.
The combination of high blood sugar and too much insulin causes oxidative stress and inflammation. This leads to tissue damage in your eyes, nerves, kidneys and blood vessels, as well as high blood pressure, hormonal issues and weight gain (when insulin can’t get any more glucose into cells for energy, it has to get it out of the bloodstream by storing it as fat).
How Can Diet Help?
Although there are some risk factors for developing type 2 diabetes that can’t be changed (such as your genetics, age and racial background), the good news is that type 2 diabetes is largely a lifestyle disease. Your diet can make a huge difference to your condition and your overall health – in fact, there’s increasing evidence that type 2 diabetes can be reversed through diet and lifestyle interventions.[*]
Eating for Diabetes and Insulin Resistance
Choosing to follow a specific diet to manage diabetes will alter the macronutrient ratios you’re aiming for or focus more or less on specific groups of foods. Still, every healthy diabetes diet agrees that it’s important to avoid:
- Refined carbohydrates (like white bread, pasta, cookies and cakes)
- Refined sugars
- Industrial seed oils (like soy and canola oil).
60% of the standard American diet now comes from these refined plant and grain products.[*] In fact, it’s been shown that traditional hunter-gatherer populations who were previously healthy, rapidly develop high rates of type 2 diabetes, cardiovascular disease and obesity when they begin eating a standard Western diet.[*]
Getting Your Macros
Macronutrient ratios are one of the key variations in different diets. No matter which diet you’re following, keep this in mind: you need a balance of all three macronutrients (fat, protein and carbohydrates) to keep your blood sugar stable.
Fat and protein help you feel full for longer, and the fibre in fruit and vegetables slows down your digestion to keep your blood sugar nice and even instead of spiking up and down.
These nutrients are often found to be low in people with type 2 diabetes:
- Alpha-lipoic acid (ALA): ALA is a fatty acid found in every cell in your body. It’s main job is converting glucose into energy, and it’s often low in people with diabetes. Your body can make ALA or get it from many common foods, such as flaxseed oil, walnuts and avocados, but you may also want to consider a supplement.
- Magnesium: Magnesium is responsible for over 300 processes in your body, including regulating blood sugar, making energy and firing muscles and nerves. Low levels are associated with insulin resistance, and people with type 2 diabetes are often deficient in magnesium.[*]
- Zinc: Chronic inflammation makes the body use up zinc faster than normal, meaning that people with diabetes are often low in zinc. The pancreas (the organ that produces insulin) also requires zinc to function.
- Chromium: Chromium is a mineral required by our bodies to help insulin regulate blood sugar levels. Supplementing chromium has been shown to help people with type 2 diabetes improve glucose and lipid levels.[*][*]
- B12 and B9: Metformin, a common medication taken to help manage type 2 diabetes, can deplete your body of vitamin B12 and B9 (also known as folate).[*]
Other Factors to Consider
- Exercise: Exercise increases insulin sensitivity. When you use your muscles, they need to take in more energy – so their insulin receptors become more sensitive.
If you don’t already have an exercise regime, you don’t need to take up CrossFit – any movement counts. In fact, exercising too intensely adds stress to your body, which could negate the benefits. One study showed that simply walking for 15 minutes after low-carbohydrate meals lowered blood glucose more than a low-carbohydrate diet alone.[*]
- Managing stress: The way our bodies respond to stress hasn’t changed since we crawled up out of the ooze. When you feel stressed – whether it’s an issue at work, a traffic jam, a breakup or an overdue bill – your body sends you into flight or fight mode. It literally prepares you to run or fight, since we evolved in a world where most stressors were trying to eat you.
Completely unaware that you can’t punch your phone bill into submission, your body releases a hormone called cortisol, which raises your blood sugar so there’s energy ready for your muscles when the fight begins. (It also turns off your digestive, immune, reproduction and detoxification systems, because you don’t need to waste energy on those if you’re about to be eaten.)
When the fight never starts, you’re left on a blood sugar rollercoaster – your body needs to lower your blood sugar again, but the stress hormones have decreased the sensitivity of your insulin receptors. It’s easy to see how chronic stress is a huge contributor to insulin resistance – and how managing your stress can have a big impact on your ongoing health.
The Best Diets to Follow
For decades, people with type 2 diabetes have been advised to follow a low-fat, low-calorie diet that focuses on weight loss. By a process of elimination, lowering fat and calories leaves a diet that’s high in carbohydrates – but high carbohydrate diets (specifically when high in starch and low in fiber) have been proven to increase the risk of developing type 2 diabetes.[*]
So, if the old way is out, which diets are in? It’s really up to you. All of the following diets show promise for helping to treat and even reverse type 2 diabetes and insulin resistance. Which one you choose will depend on your health, your goals, and the advice of your doctor.
The Mediterranean Diet is probably the most well-researched diet in the world. You’ll eat whole foods, including fruit and vegetables, lots of fish and olive oil, legumes, nuts and whole grains.
What you need to know:
The Mediterranean Diet has been shown to be more effective than a low-fat diet in lowering the blood sugar of people with type 2 diabetes[*] – and a low-carb Mediterranean diet more effective again.[*]
Low Carb Diet
Unlike the Keto diet, there’s no strict ratio of macros that defines a “low carb” diet, though anything between 75g and 150g net carbs may be considered “low carb.” Low carb diets focus on consuming protein and healthy fats, with carbohydrates coming predominantly from vegetables and fruits.
What you need to know:
Studies have found low-carb, high-protein diets to be more effective in improving metabolic health and reducing weight, as well as being easier for subjects to stick to[*] than high-carb, low-fat diets.[*][*]
Any whole food diet can be a low carb diet by choosing to limit grains and starchy vegetables – how much you limit these will depend on how you feel, your goals and your doctor’s advice.
The Ketogenic Diet is a very low-carb, high fat diet that puts your body into a state called ketosis. In ketosis, you burn fat for energy instead of glucose – check out our ultimate guide for the full low-down.
What you need to know:
The ketogenic diet has been found to be safe for people with type 2 diabetes[*], but if you’re taking medication to manage your diabetes, it’s crucial to work with a doctor or practitioner before embarking on Keto.
The Paleo Diet involves eating like our ancestors ate – processed foods, grains, dairy and legumes are out. Meat, vegetables, fruits and nuts are in.
What you need to know:
Intermittent fasting diets have lots of different names, from the 5:2 diet to the Warrior Diet, but the basic principle is the same: to lose weight and improve metabolic health through defined periods of eating and fasting. Check out our ultimate guide to intermittent fasting and keto for a deep dive into all things IF.
What you need to know:
Studies have shown that intermittent fasting may improve insulin resistance and lower glucose levels, blood pressure and total cholesterol[*][*], but it can also increase the risk of serious complications like hypoglycemia and diabetic ketoacidosis.[*][*]
If skipping a meal makes you shaky, hangry, dizzy or sick, intermittent fasting is probably not for you – yet. Work on regulating your blood sugar and developing metabolic flexibility by eating three meals a day at regular times, before slowly extending the window between dinner and breakfast.
If you’re taking medication to manage diabetes, it’s crucial to work with a doctor or practitioner when you start fasting.
The Bottom Line
Whether you’ve been diagnosed with type 2 diabetes, prediabetes or insulin resistance, the way you eat can have a huge impact on your health – and your future. A range of diets have shown promise in treating and even reversing type 2 diabetes. Which one you choose will depend on your personal circumstances and your doctor’s advice – but all of them focus on eating plenty of real, whole foods like vegetables, fruit, fish, meat and olive oil… and avoiding refined, processed food and added sugars.