On the heels of last week's entry about recommended daily protein intake, I thought it would be prudent to try and clarify misconceptions about the other two macronutrients: fats and carbohydrates.
Where protein is constantly being utilized and overturned in the human body and thus requires perpetual replenishment throughout the day, fats and carbs don't follow such rules and are subject to individual variability. For this reason, the low-carb v. low-fat diet argument continues to run in circles, so let's explore these maligned macronutrients and how they can either help or hinder our health and fitness goals.
Back in the 80s the low-fat agenda hit the mainstream media and North Americans took the bait hook, line and sinker. Fat has more calories per gram (nine) than both protein and carbs (four), so this was an easy argument to sell: taking in less fat will lead to fewer calories and body fat will drop accordingly.
The laws of thermodynamics supported this seemingly undeniable truth. However, North Americans have done nothing but get fatter and sicker since this trend occurred.
Enter the 2000s along with Dr. Atkins and the low-carb craze: It's not the fat that makes people fat, it's the carbs. Although the good doctor was onto something -- sugar is indeed a massive problem -- vilifying all carbs gave the world a complex.
We now live in a world where low-carb diet variations run amuck, low-fat diets are sworn by in the leanest community of all (bodybuilding) and every internet fitness blogger has his or her stake planted firmly in one camp or another.
Here we are, in 2016, afraid of carbs and confused about fats. Before trying to clear the muddy waters, let's investigate how we got here in the first place. The covers of Time magazine give us a nice chronological visual:
January 1961: "Dr. Ancel Keys claims saturated fats clog arteries"
March 1984: "Cholesterol: And Now the Bad News..." (Fat will kill you)
July 1999: "Cholesterol: ... And Now the Good News" (Fat isn't the problem after all)
June 2014: "Eat Butter: Scientists labelled fat the enemy. Why they were wrong."
In the span of roughly 50 years, the government and mainstream media condemned dietary fat (notably saturated fats and foods high in cholesterol) before making a now near-complete 180. In 2016 butter is no longer bad, and in case you missed the headlines, the U.S. government declared cholesterol no longer "a nutrient of concern for overconsumption" and completely removed it from their dietary guidelines.
Where we went wrong
In a nutshell, we jumped to conclusions and painted with a wide brush. Dietary fat was easy to blame given the negative connotation of the word "fat," and society ran wild with this government-approved solution.
In fairness to the government, they wanted people to eat less fat in favour of more whole grains, fruits and vegetables, which is far from malicious. The problem occurred when human nature took over and we pushed things to the extreme.
Both consumers and producers heard "all fat is bad" and "all carbs are good," so food companies took processing to a whole new level and people began justifying junk food as healthy. Dairy companies stripped the nutrient-containing fats from their products and added nutrient-devoid sugar while producers of baked goods did the same.
Before long, there was so much sugar and so few nutrients in the North American diet that obesity and disease skyrocketed.
How does this explain the rise of heart disease and cholesterol?
It's now generally understood that sugar leads to weight gain, but people haven't yet connected the dots that it's also the primary cause of high cholesterol and heart disease (not to mention cancer and countless other diseases).
Much like people were quick to believe that fat was the reason for getting fat, we also assumed that high dietary cholesterol led to elevated blood cholesterol. It is now well-known and documented that the human body produces cholesterol every day, as it is an important precursor for hormone production.
When you consume a diet high in cholesterol, your body naturally produces less endogenous cholesterol, and the total overall amount is insignificantly changed.
The harmful side of cholesterol only occurs when it gets trapped in the blood stream and plants itself on the walls of blood vessels, leading to plaque and atherosclerosis (thickening of the arteries). In a healthy human body, cholesterol will travel freely throughout. By contrast, in an unhealthy individual with inflamed blood vessels, it can get clogged up and cause major issues.
The main culprits of this inflammation are highly processed carbs such as sugar and flour, as well as pro-inflammatory omega-6 vegetable oils such as corn, sunflower and soybean oil. These ingredients are found in most packaged foods, namely things like cookies, chips and crackers, and even in some food items perceived as healthy and marketed as "all-natural" or "organic."
Excessive carbs in the diet, particularly from these poor sources, will lead to one of two things:
- Storage of new body fat
- Circulation in the blood as harmful free triglycerides, where they'll join cholesterol as plaque on artery walls
Key take-home point: Processed, packaged, man-made foods are the main cause of disease and obesity. Unprocessed animal fats are not.
If you want to avoid high cholesterol and chronic disease, your best bet is to minimize intake of sugar and processed foods (and to stay active)... But is it that simple?
Other important considerations
While on the subject of inflammation, I'd be remiss if I didn't briefly mentioned the hormone insulin. When we eat, our body releases insulin to clear glucose from the blood and shuttle the nutrients to where they're needed.
Carbohydrate-rich foods, and most notably processed carbs like sugar and flour, induce a stronger insulin response than other foods. In comparison, fats themselves elicit little-to-no insulin response.
When insulin is spiked aggressively multiple times a day, not only is the aforementioned inflammation an issue but our cells begin to become resistant to insulin, which is a precursor for diabetes and other related diseases.
In an effort to help people understand which foods spiked insulin the most, the Glycemic Index was created. Pure glucose and white bread were used to mark a top score of 100 (not good). All other foods were tested in comparison to determine how they affected blood sugar and the corresponding insulin demand; low-glycemic foods would hypothetically be "healthier" than high-glycemic foods.
Many people still believe that this Index tells the whole story, but studies are now demonstrating that this simply isn't the case.
Nobody wants to accept the answer that "it depends," but aforementioned studies are now showing that foods affect everyone a bit differently. Factors like stress, exercise and sleep can have a major effect on individual blood glucose tolerance, but genetics (and more specifically the genetic difference in our gut biomes) are major factors to consider when it comes to metabolism and health.
For example, where bread may spike insulin dramatically in some, it may elicit only a small release in others, and this can be said for all foods and food combinations. Controlling blood sugar and insulin is important for health and body composition, but we are all wired in a unique way and must individually find the foods and meals that affect us most favourably.
So what's better? Low-carb or low-fat?
Here's what we know:
- Cholesterol and fat in the diet do not directly become cholesterol and fat in the body
- Processed carbs like sugar and flour are prime offenders for obesity and disease
- Processed trans fats and omega-6 vegetable oils also contribute to obesity and disease
- Controlling blood sugar and insulin is important for health and body composition, but hormonal responses vary per individual, not universally per quality or quantity of food
To summarize, both man-made carbs and fats can be detrimental to health and body composition and should be minimized in the diet: Food quality is a key consideration. Various fat sources from whole foods are beneficial to human health (both saturated and unsaturated), as are many sources of unprocessed dietary carbohydrate.
As we've clarified, protein should be a constant in the diet: health and body composition will be best when every meal includes a source of complete protein. For this reason, carbs and fats are the macronutrients that must be manipulated when it comes to improving body composition.
Which strategy is best for you? Find out in my blog next week.
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