Thinking about reducing your carbs for weight loss but are worried about how it might affect your heart? Maybe you’re worried your cholesterol will sky-rocket?
First, let’s settle why we even consider a low-carbohydrate diet strategy: it is a dietary strategy that can achieve weight loss. The way it essentially works is by reducing the amount of processed food in our diet. Since the largest proportion of processed food in our diet is found in refined carbohydrates, reducing this macronutrient category can yield the largest return in weight loss (versus let’s say focusing on reducing the amount of processed protein in our diet).
Therefore, a low-processed food strategy is a low-carb diet strategy.
Won’t a low-carb diet strategy also mean a high saturated-fat diet strategy?
Yes, and that will be a good thing—but only if it doesn’t involve processed food (eg. bacon isn’t benign keto nation!).
First, let’s start from the beginning to understand the confusion around saturated fat. Lowering the consumption of saturated fat has been a central theme to multiple national Food Guides. Since 1980, it has been recommended that saturated fatty acid (SFA) be limited to <10% of total calories to reduce the risk of cardiovascular disease (CVD). But what is the actual relationship between saturated fat consumption (types and amounts) with the risk of cardiovascular disease in adults?”
Two years ago, JAAC published an amazing critical review to answer this and found that this recommendation was flawed. To understand why, it is important to distinguish dietary saturated fat from circulating SFAs (which can make the “bad” LDL cholesterol) in our bloodstream that creates havoc to our arteries. What we now know, is that the amount of circulating SFAs in our blood is not related to the quantity of saturated fat from our diet, but rather circulating SFAs track more closely with the amount of processed carbohydrates in our diet.
It’s not the quantity of saturated fat in our diet that matters, it’s the company that it keeps.
In our most robust meta-analysis of randomized trials, we have found no beneficial effect of
reducing SFA intake on CVD and mortality. Rather, they found dietary saturated fat intake to be protective against stroke.
What about cholesterol? Will the cholesterol increase on a low-carbohydate diet? Yes, diets higher in unprocessed saturated fat have been found to increase low-density lipoprotein (LDL) cholesterol (eg. also known as the bad cholesterol group). However, it’s not how you think. That’s because this “bad LDL cholesterol” group can technically be broken down further into two groups: the nasty LDL (small, dense) and the not-so nasty LDL (large and bouncy). The nasty LDL is capable of wedging into our arteries and clogging them, the not-so nasty LDL are too large to do that.
Diets high in saturated fat don’t increase levels of nasty LDL (small, dense), but rather the not-so nasty LDL (large and bouncy), which are much less strongly related to CVD risk.
What this means is: Whole-fat dairy, unprocessed meat, and dark chocolate are rich in saturated fats and are not associated with increased risk of CVD.
Low-carbohydrate diet strategies that are also high in saturated fat can not only promote weight loss but may also improve heart and metabolic disease—but this still depends on the type and quality of carbohydrates and degree of food processing our diet keeps. Unfortunately, food labels don’t report the degree of food processing in our foods, which is much more important than the quantity of saturated fat content in our foods.