Do Carbs Make You Fat?

So you’re afraid of going plant based because it’s inherently high in carbs. And…. carbs make you fat, right?

This is something we hear all too often. But, aren’t vegans always accused of being too skinny? I digress.

First of all, let’s address the main issue with this fear of carbohydrates. There is not one macro nutrient to blame for causing weight gain, or an increase in body fat. Extra weight from body fat or muscle comes from an excess of calories, regardless of macro nutrient origin. This means, if you eat more calories than your body burns off, whether from carbs, fat, or protein, over an extended period of time, you will gain weight. It’s the law of thermodynamics.

Secondly, carbohydrates have been unscientifically accused of causing all kinds of problems, like diabetes, inflammation, and weight gain, for too long. What’s even more misleading, is that “carbohydrates” have been lumped into the same group as carbohydrate containing foods like donuts, pastries, cookies, and other refined sugary foods. These junk foods are full of fats and oils, making a majority of their calories from fat – not carbs. Obviously this isn’t fair because we know that whole foods like rice, potatoes, veggies, and fruits are healthy despite being high in carbohydrates.

Without getting too scientific, just remember the simple fact it doesn’t matter what the macronutrient composition of a diet; the result always comes down to calories.

Carbs are the body’s preferred fuel source. Upon digestion, the body breaks these carbs down into glucose, which is either burned immediately, or stored as glycogen for later use. Sugar is the easiest source of fuel to burn, and the body doesn’t just turn it into fat. This process is extremely demanding and energy wasting.

You’re probably thinking, but aren’t carbs responsible for the blood sugar crash which leads to weight gain? Of course eating refined or processed foods can cause your blood sugar to spike and crash, inevitably leading to eating more calories. But this doesn’t happen with high carbohydrate whole foods. It’s also important to keep in mind that the more whole foods you consume, the easier it is to control your weight due to their low calorie, high fiber content. Fiber carries excess fat and toxins out of the body. Plus, fiber increases satiety, and slows down the absorption of sugar into the blood stream. So if your goal is to burn fat or drop weight, it’s in your best interest to eat more high carbohydrate whole foods.

Now, are you ready for the mind blowing info that will make you love carbs even more than you already do? People have this misconception that eating too many carbohydrates will convert to fat gain. But, there’s this mechanism in the body called de novo lipogenesis (DNL), which is basically the body’s process of turning excess carbohydrates into stored body fat. What’s so cool about DNL is that it only lets about 3% of excess carbohydrate calories get turned into body. Still, this first requires several days of overfeeding, and maxing out glycogen storage. This is very surprising since we think that all of the excess carbohydrates get stored as fat. Nope.

Remember, weight gain only happens in a caloric surplus. So say you’ve been maxing out your glycogen storage and are eating 100 calories too many on top of that. Let’s say all those excess calories are carbohydrates – no fat or protein calories at all. 3% of those calories get stored as fat, which translates to less than a gram of body fat. This means that carbohydrates barely contribute to total body fat gain compared to the other two macro-nutrients. You’d have to eat a lot of carbohydrates to gain a substantial amount of body fat.

So where does all the excess body fat come from? Well, as Dr. John McDougall says, “The fat you eat is the fat you wear.”

One of his newsletters explains it simply. “After eating, dietary fat (from lard, butter, meat, cheese, nuts, olive oil, etc.) is absorbed from the intestine into the bloodstream and transported to the millions of cells designed for storage—the body fat (adipose) cells.  The metabolic cost for this transfer is relatively inexpensive (3% of the calories consumed). No pricey chemical conversion is required, so this is a routine metabolic movement after every typical meal.  When samples of a person’s body fat tissue are chemically analyzed the results reveal the kinds of fats which that person commonly eats. For example, the consumption of margarine and shortening results in high proportions of “trans” fats in a person’s fatty tissues.  A diet with large amounts of cold-water marine fish means omega-3 fats are deposited and stored in the body fat. The saying “from my lips to my hips” expresses the real life effects of the fat-laden Western diet.  Fortunately, starches contain very little fat for us to wear.”

It’s also important to note that the populations who consume the most whole food starches, and the least amounts of saturated fats and oils, happen to be the leanest. They also have the lowest all cause mortality risks.

The moral of all this, as you already know, eat your carbohydrates freely. If your goal is to get leaner or lose weight, decrease your calories appropriately – and of course, eat your high carb, low fat whole foods. Let’s go back to common sense, which tells us that whole plants are healthy.

References:

Danforth E Jr. Diet and obesity. Am J Clin Nutr. 1985 May;41(5 Suppl):1132-45.

Thomas LH, Jones PR, Winter JA, Smith H. Hydrogenated oils and fats: the presence of chemically-modified fatty acids in human adipose tissue. Am J Clin Nutr. 1981 May;34(5):877-86.

London SJ, Sacks FM, Caesar J, Stampfer MJ, Siguel E, Willett WC. Fatty acid composition of subcutaneous adipose tissue and diet in postmenopausal US women. Am J Clin Nutr. 1991 Aug;54(2):340-5.

Baylin A, Kabagambe EK, Siles X, Campos H. Adipose tissue biomarkers of fatty acid intake. Am J Clin Nutr.2002 Oct;76(4):750-7.

Brevik A, Veierød MB, Drevon CA, Andersen LF. Evaluation of the odd fatty acids 15:0 and 17:0 in serum and adipose tissue as markers of intake of milk and dairy fat. Eur J Clin Nutr. 2005 Dec;59(12):1417-22.

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