Keto Diet for Diabetes: Help or Hindrance?

Peruse the internet, pick up a magazine or listen to the office chatter: everyone is talking about the “keto,” or ketogenic, diet. Even your local supermarket is likely carrying foods geared toward the keto diet, such as zero-carb bread and keto snack bars. What is the keto diet all about? Does it work? And, perhaps most importantly, is it safe and effective for people who have diabetes?


What is ketosis?

In order to understand what the keto diet is all about, it helps to understand the way in which this diet supposedly works. When a diet that contains carbohydrate is consumed, the carbohydrate is broken down into glucose and that glucose is absorbed through the small intestine. Cells then use that glucose for energy, and glucose not used immediately is stored in the liver and muscle tissue as glycogen.

When carbohydrate is strictly limited, the body turns to fat for fuel. Fat breakdown forms ketone bodies (acetoacetate, acetone and beta-hydroxybutyric acid) that cross the blood–brain barrier and are used as energy for the brain and the central nervous system. When ketone levels in the blood are greater than 0.5 mmol/L, the body is said to be in a state of ketosis. (By the way, ketosis is not the same as ketoacidosis, a very serious and potentially fatal condition that can occur in those with Type 1 diabetes.)

What is the keto diet?

By now, you’ve probably figured out that the keto diet is a low-carb diet. In fact, the keto diet is very low in carbohydrate, generally about 40–60 grams of carb per day or 20–50 grams of carb per day, depending on the who’s defining it. Unlike other low-carb diets, such as the Atkins diet, for example, the keto diet is also quite high in fat (70 to 80 percent of total calories).

The keto diet was used in the 19th century to help manage diabetes. In the early part of the 20th century it was used to treat epilepsy; in the 1970s, it started to gain momentum as a way to lose weight. Today, there are different types of keto diets, including versions used by athletes and bodybuilders. There’s even a vegetarian version of the keto diet. The standard keto diet is the most researched version and consists of 75 percent of calories from fat and just 5 percent of calories from carb. People generally enter ketosis after about three or four days of eating less than 50 grams of carb per day.

You can check if you’re in ketosis by checking for ketones in your urine. To do this, you dip a ketone strip (available at your pharmacy) into your urine. This is the same process that people who have Type 1 diabetes use to check for ketones.

What foods are off limits on the keto diet?

Going keto may seem like the best thing since sliced bread, but you can pretty much kiss bread goodbye on this plan. In fact, most carb foods, in general, are off limits. More specifically, here’s what to scratch off your list with a keto diet:

• Whole-grain and refined grain products (such as bread, pasta, rice, cereal, cake, cookies, candy)
• Starchy vegetables (such as potatoes, winter squash, corn)
• Legumes (beans, peas, lentils, peanuts)
• Many types of fruit and all fruit juices
• Milk, yogurt and ice cream
• Barbecue sauce, ketchup, honey mustard
• Honey, maple syrup, agave, white and brown sugar

You’ll also need to be an astute label reader and, for the most part, avoid foods that contain sugar. Additionally, you’ll need to watch your total carb intake. On the other hand, according to the keto principles, the higher the fat, the better. Some keto “experts” advise that there’s no need to worry about saturated fat intake, while others disagree and feel that focusing on healthier plant-based oils is best.

What do you actually eat on the keto diet?

By now you’ve probably gotten a sense of how restrictive this diet can be. However, there are a lot of foods that you CAN eat:

• Low-carb (non-starchy) vegetables
• Berries
• Eggs
• Meat
• Poultry
• Seafood
• Cheese
• Nuts and seeds
• Avocado
• Olive oil
• Coconut oil
• Butter
• Cream
• Unsweetened coffee and tea

What are the benefits of the keto diet?

Why might you want to go on the keto diet? Well, if you’re a child or adult with epilepsy, the keto diet has proven to be effective in helping to manage seizures, especially if medication isn’t helping. But epilepsy aside, what else might the keto diet do for you? Here’s a rundown:

• Possibly help manage other neurological conditions: Parkinson’s disease, Alzheimer’s disease, Lou Gehrig’s disease, brain tumors and autism may benefit from the use of a keto diet, although research is still being conducted.

• Lead to weight loss: You’ll likely lose weight on the keto diet, and not just because it’s restrictive. When you’re in ketosis, your appetite tends to decrease. Researchers aren’t exactly sure why this is, but it may be due to the satiating effect of a high-fat diet, a drop in the hormones that regulate hunger, ketones themselves (which can also blunt appetite) and/or an increase in the amount of calories that you burn.

• Decrease insulin resistance: When you lose weight, insulin resistance generally decreases. This means that your own (or your injected) insulin works better in the body to keep your blood sugars within a safe range.

• Improve blood sugars and A1C: Eating less carbohydrate, losing weight and a drop in insulin resistance means an improvement in both blood glucose and A1C levels.

• Lower blood pressure.

• Lower cholesterol and triglyceride levels.

What are the downsides to following the keto diet?

In many ways, the keto diet sounds like the ideal diet, given all of the possible benefits it can lead to. But despite being around for centuries, research on the impact of the keto diet in areas other than epilepsy is relatively short-term. Several of the key studies looking at this diet have only lasted up to several months; one study ran for a year. What happens after 10 or 20 years on the keto diet? In addition, one of these studies lacked a control group and included self-selected participants. And most of these studies involved a very small number of participants: It’s impossible to make widespread conclusions with just 20 or 30 people in a study. Interestingly, weight loss and other benefits of the keto diet are not much different than those of a more conventional diet after one year.

Apart from the lack of longer-term research, there are other drawbacks and possible side effects of the keto diet. From a physical standpoint, these include:

• A possible short-term “keto flu.” This occurs due to fluid and electrolyte losses as the body adapts to being in ketosis. You may feel tired, depressed and/or irritable; you may also have constipation or diarrhea, headaches and muscle cramps. These symptoms tend to disappear anywhere from a few days to several weeks.

• Increased risk of kidney stones and gout.

• Increased risk of osteoporosis.

• Possible nutrient deficiencies, such as calcium, vitamin D, iron, zinc and magnesium.

• Possible effects on gut health and the beneficial bacteria in your digestive tract.

• Possible adverse effects on LDL (“bad”) cholesterol due to a high saturated fat intake.

• Constipation.

• Bad breath.

Side effects aside, following the keto diet can take a lot of work, especially around planning and preparing meals. You’ll need to have a clear understanding of how much fat and carb you’re eating if you want to be in ketosis — this means paying attention to portions, reading labels and understanding food sources of fats and carbs. You may find that eating away from home is a challenge, as it can be difficult to find meals that work within the constraints of the diet. And if you cook for others in your household, mealtime may become an issue if your partner, kids or roommates aren’t keto diet enthusiasts.

A recent study published in the Journal of Physiology looked at the effect of the keto diet on mice. The researchers found that mice on the keto diet became insulin resistant and had a difficult time regulating blood sugar compared with mice fed a high-carb, high-fat diet. Insulin resistance is an early precursor to Type 2 diabetes. Obviously, though, this study was done with mice, not humans, and it’s too soon to determine if the same effect would be seen in humans.

What is the impact of the keto diet on diabetes?

As mentioned above, short term research indicates that the keto diet can improve diabetes control in people with Type 2 diabetes. In one study, people on the keto diet lowered their A1C levels more than people who were following the healthy plate method after 32 weeks, and half reduced their A1C to less than 6.5 percent.

Because the keto diet is so low in carbohydrate and because it can cause weight loss, it’s very likely that anyone who has diabetes and takes medication for glucose management will need a decrease, and perhaps a significant decrease, in medication. If you take insulin or a sulfonylurea such as glyburide, glipizide or glimepiride and decide to “go keto,” you need to talk with your doctor or diabetes educator prior to starting and come up with a medication adjustment plan to minimize hypoglycemia.

Who should NOT follow the keto diet?

You might be thinking, “Well, why not? I’ll try the keto diet and lose some weight and maybe lower my blood sugars.” Fair enough. But, if you have kidney disease or have had a kidney transplant, or if you have gestational diabetes or have diabetes and are pregnant, you should avoid the keto diet. Period. What if you have Type 1 diabetes? Some experts say it’s not a good idea to go keto with Type 1 diabetes because there is a risk of kidney damage. Bottom line: Talk with your doctor first before embarking on this eating plan.

Is the keto diet for you?

You may be very tempted to try this diet, especially given all the hype and the accolades that it’s been getting. Some food for thought:

• Talk with your health-care team to get the green light.

• Ask yourself if you’ll be able to follow this diet to the letter — even small carb excursions can quickly bring you out of ketosis.

• Also, ask yourself if this way of eating is sustainable in terms of enjoyment, social events and cost.

• Be prepared to check your blood sugars often and to stay in close contact with your doctor for possible diabetes medication adjustments.

• Be on the lookout for short and long-term side effects.

• Meet with a dietitian who is familiar with and supportive of the keto diet to get you started.

Want to learn more about low-carb diets and diabetes? Read “Carbohydrate Restriction: An Option for Diabetes Management,” “Low-Carb Diabetes: What You Need to Know,” “More Evidence Supports Low-Carb Diet for Diabetes,” and “Can a Very-Low-Carb Diet Help People With Type 1 Diabetes,” then try one of our top seven low-carb recipes.

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