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Oh, the carbohydrate versus fat war! This has long been a hot topic in our society and spurred many a new diet book based on the premise that either fat or carbohydrate somehow causes more weight gain or weight loss than the other.

This is particularly relevant for people with diabetes (PWDs) because additional carbohydrates are often needed to treat low blood glucose or match insulin doses, causing worries about unwanted weight gain or ill effect.

This controversy stems back to the 1970s when the “diet-heart hypothesis” was introduced and North Americans were encouraged to adopt a super low fat diet to manage cholesterol. We now know that not all cholesterol is bad, that saturated fat alone may not be responsible for heart disease as we once thought, and that low fat food products are not necessarily the healthier choice.

This “macronutrient war” led to research studies to determine any “metabolic advantage” to a low carb versus low fat diet.

The results? Generally, people on the low carb diets lost more weight in the short term, but several studies that followed subjects for a longer time showed that the effects began to diminish around the 24-month mark as people started to consume more carbs. Change to other health markers like cholesterol were not significantly different in either group.

Meanwhile, a 2017 research review evaluated 32 different controlled diet studies, and found that when calories and protein are controlled, there is no energy expenditure or weight loss benefit from eating a low carb diet.

In the end, weight management comes down to overall calorie control.

While it’s true that calories from different foods provide different micronutrients and have a different impact on your body’s biological processes, to say that one source of calories causes more weight gain than another is a fundamental misunderstanding of the laws of thermodynamics.

Carbs have 4 calories per gram and fats have 9 calories per gram. Even the fact that fat is more calorically dense doesn’t mean it is somehow more likely to cause weight gain. Nutrition is all about context.

The thing about weight loss and diets is that it’s all about math, really. If you are taking in more calories than your body needs or is burning regularly over time, weight gain will likely result. And if you’re consuming fewer calories than your body needs over time, the opposite will likely occur. This can get a little complicated to quantify because it’s easier to track the calories going in than the exact amount of energy you’re expending (since everyone’s reaction to physical activity is different).

Hayden James, a registered dietitian and diabetes care and education specialist (DCES) with Intermountain Healthcare in Utah, sums it up well. She says, “Neither carbs nor fats alone cause weight gain. It comes down to total calories. Finding a balance of the two that works for the preference that helps you reach your goals is key.”

PWDs are often concerned about the use of insulin causing weight gain, and the more carbs one consumes the more insulin needed. This is the central thesis of the “carbohydrate-insulin hypothesis of obesity” which was disproven. Neither carbs nor insulin are solely responsible for weight gain. In fact, they both have a job to do in maintaining normal functioning of the human body.

Mary Ellen Phipps, registered dietitian and author of The Easy Diabetes Cookbook, explains: “The classic example — and honestly the easiest to understand — of how insulin works is a lock and key. After you eat carbs, or after your liver produces glucose, you’ll have glucose molecules floating around in your blood stream. Your body’s cells need this glucose, but they can’t just walk right into cells. They’re locked. They need a key. So, your pancreas produces insulin that is released into your blood stream and acts like a key on cells to let glucose in. Diabetes results when you have a deficiency of insulin, ineffective insulin, or both.”

It is true that if there’s an excess of carbohydrate in your body that cannot be utilized or stored as muscle or liver glycogen, it will be stored as fat. But the body’s fat stores are in a constant state of flux. While perhaps one stores some carb as fat during one point in a day, at another point that fat may need to be mobilized for energy when other fuel sources are not available.

For people who want to lose weight, we have to take a look at the science around weight. “Set point theory” states that your body has a preset weight baseline hardwired into your DNA, and how much your weight changes from that set point might be limited.

The theory says some people have higher weight set points than others and our bodies fight to stay within these ranges.

But there’s also evidence that weight set point can be nudged higher by chronic dieting, weight cycling, etc. This contributes to the high percentage of individuals who regain weight post-diet. A 2018 research review showed a near-ubiquitous pattern of “diet interventions” typically resulting in early rapid weight loss followed by a weight plateau, and then progressive regain.

This helps illustrate that making weight loss a continual goal is generally unsustainable. It’s also important to recognize that weight loss is not necessarily the answer to “solving” health conditions that can be helped with other behavioral and lifestyle changes.

This gets even more complicated by the fact that weight is not synonymous with body composition, which is the proportion of muscle, fat tissue, and bone/mineral/water in the body. This is a big reason why using BMI (Body Mass Index) to measure someone’s “health” is so flawed. BMI is just an equation that compares weight to height and can’t differentiate body composition, which is more closely linked to overall health than weight alone.

In other words, bodies come in all shapes and sizes, and we cannot determine someone’s health by their weight alone. In fact, it turns out that waist circumference is more useful than BMI in determining a person’s risk for disease. But neither measure considers the whole person.

Health at Every Size (HAES) is an initiative that promotes behaviors with the goal of overall health, not just weight loss. Dr. Gregory Dodell of Central Park Endocrinology in New York is a self-proclaimed HAES nondiet endocrinologist.

He suggests a “weight inclusive approach” focusing on health-promoting behaviors such as stress management, movement, intuitive eating, and sufficient sleep irrespective of weight. People may lose weight, gain weight or remain the same weight in the setting of an improved lifestyle that results in improved glycemic control.

Clearly, for PWDs, the carbs/fat/insulin question is not just about body weight, but also about the impact on blood glucose (BG) control.

There is evidence that replacing carbohydrates with more unsaturated fat in your diet (as in the Mediterranean diet) helps improve insulin sensitivity — meaning you need less insulin to achieve target BG control.

And there are also ways to improve BG control and lipids without weight loss, like getting more exercise and sleep (many people need more of both), increasing fiber intake, reducing simple sugars, etc.

It is often thought that many doctors and diabetes educators in large diabetes centers are advocating high carbohydrate diets that make BG control difficult.

But this is increasingly not the case.

For example, New York endo Dr. Dodell encourages his patients to “combine fats, proteins and fiber to carbohydrates to help prevent blood sugar spikes rather than restricting or eliminating carbohydrates. Adding nutrients rather than subtracting is perhaps a more sustainable approach since evidence demonstrates that restrictive diets are not sustainable long-term.”

The American Diabetes Association (ADA), long criticized for not acknowledging the benefits of low carb eating for glucose control, currently suggests that nutrition should be individualized for PWDs and there is no ideal percentage of carbohydrate, protein, or fat in the diet.

Amanda Ciprich, a registered dietitian in New Jersey who lives with type 1 diabetes (T1D) herself, says that the ADA now “recommends that individuals meet with a doctor or dietitian to explore which (eating) approach is best for them — which is important, since there isn’t a one-size-fits-all-approach to diabetes management.”

Dietitian Phipps, for one, is pleased that the ADA is now taking this approach. “While recommendations from professional organizations are catching up, historically they don’t keep up with the science as quickly as we’d like,” she noted.

There is a large movement that centers around the “Bernstein Method,” which is low carb diet, calling for only about 20 grams of carbs per day. It’s true that this diet shows the production of “on target” glycemic control, but Phipps points out that “while this may be an effective approach for some, it is not the one and only way to eat if you have diabetes.”

Julie Stefanski, registered dietitian, DCES, and spokesperson for the Academy of Nutrition and Dietetics, agrees. She says that “as valid research continues to emerge supporting use of ketogenic diet therapies, it’s important for dietitians to be knowledgeable regarding diet guidelines and pitfalls for those individuals wanting to replicate the success of this research in their own lives.”

The fact is that while low carb diets can be used to control blood sugar, this restriction often causes deprivation that leads to overeating or binging. PWDs are not exempt from this psychological phenomena.

It’s just not realistic for most individuals to NEVER enjoy a cookie, a slice of bread, or a piece of birthday cake. Some individuals can take on this way of eating for long periods of time. But others may start experiencing a decline in mental and physical health, leading to unintended weight gain via the “binge-restrict” cycle.

There is a very high prevalence of both disordered eating and eating disorders in PWDs. The National Eating Disorders Association defines “disordered eating” as eating out of boredom, anxiety or social pressures, versus an obsessive eating disorder.

In fact, eating disorders co-occur so often with diabetes that the phenom has been labelled by the media as “diabulimia.” This often results from the well-intended but stringent dietary recommendations made to help control BG, particularly in type 1 diabetes (T1D).

Clearly, we must consider the total cost of aiming for “perfect blood glucose control.” A 2019 research review showed that women with T1D are 2.5 times more likely to develop an eating disorder than someone without diabetes.

In a previous article about how low carb diets can sometimes backfire for people with T1D, I discussed this concept. People can choose any dietary pattern, but in my opinion, if the diet is causing anxiety, binging, fear of eating out or socializing, etc., then it may not the ideal diet. Stress and anxiety also impact glycemic control, so this is something important to consider when evaluating total health and wellness. Always talk with a healthcare professional about your dietary needs or any changes you make to your diet.

While diabetes (and food allergies, etc.) are chronic conditions, food is also social, emotional, and cultural. Unlike a food allergy where total avoidance is required, insulin allows individuals with diabetes to enjoy carbohydrates in moderation, and this shouldn’t be viewed as something negative or harmful.

It’s not the carbs OR the fat that is better for weight loss, as there are a host of other factors determining one’s body weight and overall health.

Focusing on adequate nutrition, sleep, stress management, and a healthy relationship with food and your body will help an individual more than just honing in on dropping a certain number of pounds.

The focus on self-care and positive food and body behaviors may result in weight loss, weight gain, or staying the same. But positive changes to daily well-being and glycemic control can be an even bigger win than just weight loss.

Christina Crowder Anderson is a diabetes care and education specialist (DCES) and pediatric registered dietitian nutritionist. She takes a no-nonsense, evidence-based yet open-minded approach to nutrition in her virtual private practice. In her leisure time, she enjoys spending time with her husband and her dog Cooper, along with cooking and judging Junior Olympic/NCAA gymnastics.