Low-carb diets seem to have made a comeback—Atkins, Paleo and more recently the ketogenic diet—all follow a low carbohydrate regimen and claim greater weight loss and even improved glycemia in people with diabetes.
While there is no doubt that carbohydrate restriction has the most significant improvement in blood glucose (since foods that contain carbohydrates can spike blood sugar after meals or snacks), the question remains: What is the “ideal” grams of carbohydrate for people with diabetes to consume?
According to the American Diabetes Association 2017 Standards of Care, “there is no single ideal dietary distribution of calories among carbohydrates, fats, and proteins for people with diabetes." The previous recommendation of 45-60% of calories from carbs is no longer supported by evidence. Instead, the distribution of carbs, protein, and fat should be individualized "while keeping total calorie and metabolic goals in mind.” What works for one person with diabetes, might not work for another.
Still, ketogenic diets have gained popularity thanks to celebrities like Lebron James and Kim Kardashian claiming superior athletic performance, mental well-being, and faster weight loss.
The medical community is even testing the effects of the ketogenic diet on cancer, Alzheimer's and Parkinson's disease. The ketogenic diet seems to be trending now, but is this diet really safe for people with diabetes? Here's what the research says:
What is the Ketogenic Diet?
Believe it or not, ketogenic diets go back to the 1920’s and remain one of the oldest treatments for epilepsy in children. Researchers don’t know why this diet works, but it’s shown to decrease seizures and seizure medications in children with epilepsy. But, unlike a low-carb diet, which may vary in the number of carbohydrates allowed, the ketogenic diet is a high-fat, low carb diet that severely restricts carbs to no more than 20g per day. (That's just one medium orange, a potato or half of a hamburger bun, folks!) The main purpose of this diet is to generate a state of ketosis which leads to the body burning fat instead of glucose for energy.
According to Lisa Cimperman, RD, former spokesperson of the Academy of Nutrition, “Ketogenic diet regimens cut carbs to less than 50 grams per day. The intention is to force the body to utilize fat to produce ketones for energy”. People with type 1 diabetes may be familiar with ketones and even diabetic ketoacidosis—which is often the way newly-diagnosed type 1 diabetes discover their problem. But dietary ketosis and ketoacidosis are not the same.
Diabetic Ketoacidosis, or DKA, is a life-threatening condition that occurs when the body produces high levels of ketones, usually due to a lack of insulin. Ketosis is a physiologic process that happens when the body does not have enough glucose fuel for energy, so uses fat as fuel instead. The result is a buildup of fatty acids in the body known as ketones. Put another way, the body is forced to use its own fat burning mechanism as fuel rather than using glucose from food. As a result, the body uses less insulin.
Around 80% of the ketogenic diet comes from fat. Ideally from healthy, unsaturated fats like avocado, olive oils, nuts, nut butter. It allows for moderate protein consumption and no more than 20 grams of carbohydrates.
It cuts out all fruits, starches, milk and yogurt, grains, potatoes, and beans. Keto diet staples include:
Losing weight is one of the toughest challenges for people with or without diabetes and maintaining the weight loss is equally as difficult. Not surprisingly, around 80-90% of people living with type 2 diabetes are overweight or obese. Some estimates report up to 60-80% of individuals who lose weight regain it after a few years.
Both very low carb and ketogenic diets are often touted as superior ways to lose fat and increase insulin sensitivity, the dietitian reports. “The theory is that a high level of carbohydrate intake promotes insulin secretion, which in turn, results in the storage of body fat. Conversely, low-carb intake promotes decreased insulin levels, increased breakdown of body fat, and subsequent weight loss,” Cimperman says.
One study, published in the New England Journal of Medicine attempted to answer the question: Is low-fat or low-carb better for weight loss? The study randomly assigned 132 obese subjects to either a low fat or a low carb diet for six months. Subjects on the low-carbohydrate diet lost more weight and had greater improvements in triglycerides and insulin sensitivity.
Other research on men shows that when the body is in ketosis, there is a decrease in hunger, which is a possible explanation of why people lose more weight on a ketogenic diet. Similarly, a 2013 systematic review of 13 ketogenic studies concluded that very low carbohydrate diets achieved more favorable effects on weight loss, body composition, and other metabolic indicators.
Type 2 diabetes is characterized by carbohydrate intolerance or the “inefficient use of insulin by the body.” So, when carbohydrates are reduced, insulin resistance improves.
Studies of ketogenic diets in subjects with type 2 diabetes show acute improvements in insulin sensitivity, A1C, and lower doses of medication compared to conventional diets. A randomized study done in type 2 overweight subjects compared the safety, tolerability, and benefits of a ketogenic diet to a low-calorie diet and found improved A1C and greater weight loss in the ketogenic diet.
The biggest driver of glycemic improvements is presumed to be weight loss. However, even in the absence of weight loss, studies have shown favorable metabolic effects in hemoglobin A1C, insulin concentrations, and reductions in medication use. Nevertheless, the improvements in glycemia disappear after one year or more. That is to say, the ketogenic diets produced the fastest improvements in diabetes control and weight loss, but long term, the ketogenic diet did not show superior benefits when compared to low-fat diets.
Why Keto Diets Are so Hard to Follow
There are several drawbacks to the keto diet.
Current research tells us that overweight individuals with type 2 diabetes (or at high risk) will lose weight faster when following a ketogenic diet or low carb diet. What we still don’t know is for how long the ketogenic diet can be sustained.
A study done in 2003, conducted a one-year randomized study in obese participants on either a high-protein, low-carb Atkins diet vs. a low calorie, higher carb conventional diet. Subjects on the Atkins diet lost more weight compared to the conventional diet at three and six months, however, by one year the difference disappeared.
Participants achieved a faster weight loss in the first 3-6 months, but by one year both diets were equal despite the differences in nutrient composition (fat, protein and carbs).
#2. Adverse effects
According to Robin Nemery, MD, pediatric endocrinologist at Joe DiMaggio Children’s Hospital in Hollywood, Florida, “Ketones are acids in the body. People don’t feel well when they are in ketosis”. The body is most efficient in burning carbohydrates as energy rather than fat. “So it’s not innate for our bodies to go through this process,” Dr. Nemery says.
Another 2003 study, reported significant adverse effects (80%) in subjects following a very low carb diet (VLCD) compared to subjects on a low-calorie diet (41%), despite seeing improvement in weight loss. Symptoms included nausea, headache, vomiting, and constipation.
It is important to note, many of these research studies are done in a hospital setting under close supervision, where doctors monitor specific labs before starting and after initiation.
Medications will likely need to be adjusted when following very low carbohydrate and ketogenic diets, so it's important to consult your healthcare provider before starting such diet.
#3. Increased cardiovascular risk
Experts have raised concerns about increasing cardiovascular risk due to the reliance of fat in the diet. Saturated fat increases in ketogenic diets but studies remain inconclusive regarding the effect of carbohydrate restriction on cholesterol, triglycerides and overall heart health.
A ketogenic diet is another form of a low-carb diet that relies on the presence of ketones in the body. In individuals with type 2 diabetes, following a low carb diet offers greater benefits in both weight and glycemia.
Does the ketogenic diet produce rapid weight loss results? Yes. But at what cost? Additionally, the long-term feasibility is still unclear. Can you go an entire lifetime by just eating one slice of bread per day? I’m not so certain, nor do I think that should be the message given to people with diabetes.
“There is a nutritional benefit in consuming high-fiber carbohydrates such as whole grains, fruits, and vegetables,” points out Dr. Nemery. “I often question if there is more harm than benefits when exposing the body to the drastic and acute changes like those in really low carbohydrates diets.”
Ketogenic diets often need to be supervised as the medications are often reduced. Research studies have not shown benefits in people with type 1 diabetes, as most studies are done in overweight adults with type 2 diabetes it's not recommended for the T1D population.
Does a low carbohydrate diet have to be under 20g of carbs to offer health benefits? Choosing a smart meal plan that includes high fiber, low glycemic (or good quality) carbs such as sweet potatoes, yogurt, berries, lentils, and oatmeal may be a more sustainable approach.
At the end of the day, the best diet for people with diabetes or anyone is the one they can follow long-term, not just for three months!