I hear a lot about the benefits of low-carb diets these days. Years ago it was all about low-fat. I decided to explore this debate in a recent Nutrition 101 column. Enjoy!
The Low-carb vs. Low-fat debate
It’s one of the age-old debates in nutrition – what diet is healthier and/or helps you lose more weight, low-carbohydrate or low-fat? It seems almost everyone has an opinion, with fervent supporters of both approaches, but let’s take a look at what the science says.
Low-carb vs. Low-fat
For the purpose of this discussion we should probably first try to define what we mean by low-carb and low-fat diets. Lending to the confusion there isn’t a consensus definition, but generally speaking with low-carb diets, carbohydrates make up < 10% (very low-carb) or < 45% (low-carb) of the total calories. In low-carb diets fat can make up as much as 50-60% of the total calories. In terms of food, low-carb diets tend to limit or eliminate grain products, dairy, fruit and legumes. Conversely, in low-fat diets, carbohydrates make up 45-65% of the total calories, whereas fats make up 20%-35%. Low-fat diets suggest avoiding foods like butter/oils, fatty meats and full-fat dairy.
Low-fat diets first made their appearance in the 1960’s after research showed that fat intake was associated with higher cholesterol levels, a major predictor of cardiovascular disease. Over the subsequent years low-fat diets were touted not only for heart patients, but for weight loss and general health as well. By the 1980’s low-fat was all the rage in the burgeoning nutrition industry. It was around this time that Dr. Robert Atkins catalyzed a movement against low-fat with his self-titled, low-carb Atkins Diet. Part of the appeal of The Atkins Diet was that it featured many foods low-fat dieters were expected to avoid. Since then low-carb and low-fat diets have been re-packaged numerous times to varying degrees of success.
Over the past 30 years there have literally been thousands of studies that looked at the benefits/effectiveness of both diets, using many different health indicators including weight loss, various metabolic risk factors and others. Unfortunately, there is no clear consensus on the best diet overall, but a few interesting truths have emerged. 1) Low-carb diets do not appear to increase the risk of cardiovascular disease as originally feared 2) Weight loss can be achieved with both calorie-restricted low-carb and low-fat diets 3) Low-carb diets seem to provide a greater degree of weight loss in the short-term, however neither diet is particularly effective in doing so in the long-term. 4) Poorer outcomes, including the ability to follow the diet, are associated with more extreme versions of low-carb and low-fat dieting.
What does this mean for you?
Rather than focusing on the percentages of carbohydrates and fats in your diet, it’s probably better to focus on the quality of fat and carbohydrate that you’re eating. What do I mean by this? Whenever possible, eat real food that has been prepared using unprocessed ingredients and avoid foods with unnecessary added fats and sugars (aka. carbs). If weight loss is your goal, overall calories are much more important than the relative amounts of carbohydrates and fat in your diet.
If you’re set on trying to go low-carb or low-fat, make sure you do your research. Avoid diets that appear overly restrictive and only choose plans than you can envision sticking with indefinitely. At the end of the day, both low-carb and low-fat diets have their merits, but as with most things in life, balance is key.