Cutting Back on Carbohydrates Heals Diabetes

Dr. Lee As of 2024, more than five million people in Korea alone are living with diabetes. The number of patients with diabetes among those aged 30 and over reaches 5.33 million. And these days diabetes is no longer a disease of the elderly. According to the Korean Diabetes Association, more than 300,000 young adults between 19 and 39 are now diagnosed. What is even more troubling is that childhood diabetes is also on the rise.

Dr. Lee Diabetes is a worldwide problem. According to the World Health Organization, 800 million people — about 10 percent of the world's population — have diabetes. That figure has quadrupled in just 32 years. When diabetes is left untreated, the small and large blood vessels begin to deteriorate and complications appear. Vessel-rich organs such as the brain and the kidneys are damaged, leading to cerebrovascular disease, kidney disease, and cardiovascular disease. Peripheral tissues can become necrotic, sometimes requiring amputation of the hands or feet, and many people lose their sight when the optic nerve is damaged.

Dr. Lee So is diabetes incurable? Once you understand its cause, it turns out to be remarkably easy to improve. Even the meaning of the word tells you what to do. The Korean term for diabetes literally means glucose appearing in the urine. So why does glucose spill into the urine? Glucose is an important energy source for the body, so why would the body discard it? It does so because there is far more glucose in the body than it actually needs.

Dr. Lee There are two main reasons why glucose accumulates beyond what the body needs. The first is that the pancreas has failed and is no longer secreting insulin — this is called type 1 diabetes. Insulin knocks on the doors of cells and signals them to take up glucose. When insulin is lacking, cells do not open their doors, so glucose concentration in the blood keeps climbing to dangerous levels. The second reason is consumption of more carbohydrate than the body needs — this is type 2 diabetes, which accounts for the great majority of cases. Carbohydrate is broken down into its basic unit, glucose. So the first step in addressing diabetes is to reduce the intake of carbohydrate. Foods rich in carbohydrate are grains and starches: rice, barley, wheat, Job's tears, corn, potato, and sweet potato. From these are made breads, cookies, ramen, noodles, rice cakes, cakes, syrups, sugary drinks, hamburgers, glass noodles, pasta, and so on.

Zoe Doctor, even in foreign films and morning dramas these days you often see people having a quick breakfast of cereal with milk. A yoga teacher I know does the same. Is that bad for diabetes?

Dr. Lee Yes, it is. Looking at Table 7-1, corn cereal contains 88.05 g of carbohydrate per 100 g, and brown-rice cereal contains 85.33 g. Eating foods like these inevitably causes blood glucose to spike. Even at temples, monks often eat porridge for breakfast — but since the main nutrient there is carbohydrate, the risk of developing diabetes is also raised. In Table 7-1 brown rice is listed at 34.3 g per 100 g, but if you account for the 60 g of water, you can see it is also high in carbohydrate. Wheat-based crackers are 84 g carbohydrate per 100 g, and scorched-rice nurungji is 90.98 g.

Emily If even nurungji is 90 percent carbohydrate, I will have to be careful about how much I eat.

Dr. Lee So if we don't eat carbohydrate, how can the body get the nutrients it needs? The answer is the ketogenic diet. You simply lower the share of carbohydrate and raise the share of fat — a remarkably simple change. Studies report that this kind of ketogenic diet improves not only type 2 but also type 1 diabetes. So make nuts, seeds, and beans the active core of the menu, and bring in a wide variety of vegetables, fruits, and seaweed. Nutritionally it is actually richer, and the meals you create end up tasting better, looking better, and smelling better too.

Macronutrient Profiles of Nuts, Fruits, Vegetables, and Grains

Zoe Doctor, could you tell us the carbohydrate, fat, and protein amounts of nuts, seeds, and beans? That would help.

Dr. Lee Of course. Knowing the actual numbers helps when you build daily menus. In Table 7-4, pecans contain 13.6 g of carbohydrate per 100 g, while fat is 74.3 g — a remarkable 668 kcal from fat. Other nuts show similar profiles. Because nuts, seeds, and beans are calorie-dense, you do not need large portions, so you also avoid the post-meal drowsiness that comes from heavy carbohydrate meals.

Dr. Lee On top of that, you can use a wide range of vegetables. Vegetables are mostly water — over 95 percent. In Table 7-3 aloe is 99.1 percent water, and even kimchi is 97 percent water. So when nuts, seeds, and beans are paired with a generous variety of vegetables, you have a wonderful ketogenic menu. Fat also stimulates the hypothalamus to suppress appetite, so weight loss follows naturally.

Susan I had understood diabetes as a disease in which there is too much sugar in the blood and so it appears in the urine. Blood glucose comes from the breakdown of carbohydrate. So if you eat nuts, seeds, and beans, which are low in carbohydrate, the blood-sugar level naturally falls and diabetes naturally improves.

"Effect of the Ketogenic Diet on the Prophylaxis and Treatment of Diabetes Mellitus: A Review of Meta-Analyses and Clinical Trials" (Dyńka et al., 2023)

Dr. Lee Exactly. Many scientific studies have already reported the beneficial effects of the ketogenic diet on diabetes, and the evidence keeps accumulating. Today let's look at a few of those studies. The first paper is "Effect of the Ketogenic Diet on the Prophylaxis and Treatment of Diabetes Mellitus: A Review of the Meta-Analyses and Clinical Trials" (Dyńka et al., 2023).

Dr. Lee This study began by analyzing how many papers had been published on the topic of ketogenic diets and diabetes. As Figure 7-1 shows, before 2017 there were no more than ten papers per year. In 2018 the number suddenly exceeded twenty, and by 2020 there were about forty papers on type 2 diabetes and the ketogenic diet, and about twelve on type 1 diabetes. This sharp rise itself is evidence that the ketogenic diet works for diabetes — it shows that interest is growing among the public and that researchers are accumulating scientific evidence.

Zoe Wow — papers really started multiplying from 2018 onward. Maybe it is only natural that the public still does not know about the benefits of the ketogenic diet. The research itself is so recent.

Dr. Lee Yes. But it has caught attention in the West for its weight-loss effect, and in Korea it is widely known as "low-carb, high-fat." The catch is that most of those approaches use animal foods, so the benefits of plant foods are missed. Even so, researchers are reporting a wide range of effects. The authors follow with a table of ketogenic-diet outcomes in children with type 1 diabetes (Table 7-5). Many of these children showed reduced seizures, better cognition, and stabilized blood sugar. Some saw improved developmental outcomes and better growth velocity, and in some papers the daily insulin dose was reduced. The authors then turn to type 2 diabetes. With a ketogenic diet, blood glucose and HbA1c fell. So did body weight and BMI. Triglycerides went down, and the "good" HDL cholesterol went up.

The Diverse Positive Effects of the Ketogenic Diet on Diabetes

Dr. Lee The authors offered several explanations for why the ketogenic diet produces these positive effects in diabetes. As Figure 7-2 shows, the diet lowers blood glucose, lowers HbA1c, lowers blood insulin, improves blood-sugar control, improves insulin sensitivity, reduces body weight, improves the lipid profile, and reduces the dose of insulin and other medications. There are surely other factors as well, and we'll meet some of them as we look at other studies.