Let's Stop The Keto Madness. Carbs Don't Make You Fat, And Here is Proof
Unless you have been living underneath a rock for decades, you most certainly have heard the demonization of carbohydrates. It seems as though every month there is a new fad diet, ridiculous documentary, or "study" that suggests that the consumption of carbs is, indeed, the reason why you are not losing weight. What all these aforementioned things don't tell you is the actual truth. They pick and choose data without telling the full story. This article will put all of this nonsense to rest, and will look at what scientific research actually says about the relationship of the consumption of carbohydrates with weight loss/weight gain.
Is This a Carb?
Before I dive deep into the data and science I want to make something clear, because there seems to be a misunderstanding. What an actual pure carbohydrate is gets misinterpreted, and tends to get mistakenly categorized. For example:
· hot cheetos
· ice cream
· any other of the tastiest foods
Carbohydrates right? Not exactly. What people don't realize is that these foods contain the same, if not more, amount of calories from fat than they do from carbohydrates. Because they have a large portion of fat, they ultimately are very calorically dense for a small volume of food. Yet, they get categorized as a carb and, subsequently, demonized into the "carbs are evil" camp.
It is not that carbohydrates are evil; it is that the above-mentioned foods are not necessarily a pure carbohydrate.
What is a pure carbohydrate? (list is not comprehensive)
· apple (all fruits)
· broccoli (all non-startchy vegetables)
· potatoes (real potatoes, not deep fried french fries)
These aren't exactly the foods you tend to think of when you think of indulging and weight gain is it? Well, these are real carbohydrates. These are not as calorically dense and tasty as the previous list because they contain practically no fat.
Now that we have that settled, let's move on to some large population data to see the impact pure carbs have on obesity.
Carbohydrates cause weight gain they say. If this is true, then we should be able to see a clear cause-and-effect relationship between consumption of carbohydrates and obesity rates. Let's take a look at some charts to see if this is true. Warning: Keto-lovers, cover your eyes.
Interestingly, the carbohydrate intake actually decreases in 1999 while the obesity rates continue to climb. Hmm. Not exactly what carb-hatin' advocates want to see, is it? If carbohydrates were, in fact, the direct cause of weight gain, then as the carb intake decreases post-1999 then so should have the obesity rates. However, this is not the case.
"Well, it's not carbohydrates that make us gain weight, its sugar." I have heard this one many times as well. To be clear, by the way, sugar is a carbohydrate. But, anyway, let see if this statement holds any ground.
Woops, wrong again. Similar to carb intake, sugar intake decreases while the obesity rates continue to rise. How could this be? Because, despite what you might have heard, carbohydrates/sugar are only part of the obesity story.
Collectively, these two charts clearly make the whole "carbs make you fat" argument quite weak, and demonstrate that it is based on people's personal nutrition myths and beliefs rather than what data actually shows.
Carbs are, however, a contributor to weight gain by virtue that they are only one of three macronutrients that provide calories, but clearly shouldn't be demonized as the sole reason for obesity.
What Does Science Say?
Now that we have looked at some large population data that debunked carbs as our weight loss enemy and the sole cause of obesity, let's see what scientific research on individuals says.
This list is by no means exhaustive, but I think you will get the point.
A study in the American Journal of Clinical Nutrition examined the long-term effects of very-low carbohdyrate weight loss diet compared to a higher carbohydrate intake diet. 118 men and women were either assigned to a energy-restricted very low carbohydrate diet (%4 of their total calories came from carbs) or to a energy restricted higher carb intake diet (46% of their total calories came from carbs) for 1 year. Simply, one group had only 4% of their calories from carbs, and the other 46%.
Results: Both resulted in similar weight loss and changes in body composition. There were no significant difference between the low and high carb groups in weight loss.
Conclusion: Under caloric restriction, it does not matter whether its low carb or high carb for weight loss. What matters is calories.
Another study in by the New England Journal of Medicine aimed to demonstrate the effectiveness of a low carbohydrate diet for obesity. This study composed of 63 men and women were assigned to either a very low 20g /day carbohydrate group or a high 60% of total daily calories of carbohydrate group. Women were on restricted calories of 1200-1500 calories per day and men were on 1500-1800 calories per day. The study was performed for 1 year.
Results: After 1 year both lost similar weight, but there were no significant differences in weight loss between the groups.
Conclusion: The amount of carb intake did not make a difference in weight loss after the 1 year period. Both groups lost weight due to the fact that they were on a calorie-restricted diet, not because of total carb intake.
Not convinced yet? No worries, here are more.
Another study in the Annals of Internal Medicine had similar results. 307 participants were either in a low-carbohydrate intake (20 g/d for 3 months). After 3 months, participants in the low-carbohydrate diet group increased their carbohydrate intake (5 g/d per wk) until a stable and desired weight was achieved. The higher carbohydrate group was assigned a diet that consisted of 55% of their calories from carbohydrate. Woman were on restricted calories of 1200-1500 calories per day and men were on 1500-1800 calories per day. This study was performed for 2 years.
Results: There were no differences in weight or body composition between the groups at any point.
Conclusion: Both groups did lose weight, however the carbohydrate intake, once again, did not make a significant difference in how much weight was lost. Both groups lost weight due to the fact that there were on a calorically restricted diet, not because of carb intake differences.
Another year-long study involved over 600 participants (263 male and 346 female). This study was conducted by Dr. Christopher Gardner of Stanford University in conjunction with the US National Institutes of Health (NIH), the Nutrition Science Initiative (NuSI), and a team of nutrition experts. A very low carbohydrate, moderate- fat diet was compared to a higher carbohydrate, low- fat diet.
Results: Weight loss was achieved by both groups, however, the study showed no significant weight-loss differences between the low-fat and low-carb groups.
Conclusion: The results of this study contribute to a large body of evidence indicating that, for weight loss, neither low-fat nor low-carb is superior (as long as there’s no difference in caloric intake or protein intake).
Let's take this even one step further. If it's not carbs that make you fat than it must be sugar, right? Well, let's see what research shows.
A study in the American Journal of Clinical Nutrition consisted of 42 overweight female participants were prescribed a low or high-sucrose (table sugar) diet. all meals were provided for a 6-week period to ensure accuracy. Both diets contained approximately 1100 calories and 19% of calories from protein and 71% of carbs. The high-sucrose diet contained 43% of the total daily energy intake as sucrose; the low-sucrose diet contained only 4% of the total daily energy intake as sucrose. In other words, one group had 43% of their total caloric intake come from pure sugar and the other group only 4% came from pure sugar.
Results: Both groups lost weight, but there were no significant differences in weight loss or body composition. Results showed that a high sucrose content in a caloric deficit did not adversely affect weight loss.
Conclusion: Not only do carbohydrates not matter when calories and protein intake are controlled, but not even the type of carbohydrate matters when the calories and protein intake are controlled in terms of weight loss.
Bottom line: A mountain of evidence supports the idea that when caloric intake (and protein intake) are both equated between the diet interventions, the amount of carbohydrates makes no significant difference for weight loss. There is no need to extremely restrict carbohydrates if you control your caloric intake, period.
What is the cause of weight gain?
So far we have learned that in large population data, carbs failed to show a clear cause-and-effect relationship to the rise of obesity/weight gain. We also learned that in clinical research trials, the manipulation of high or low carbs failed to show any significant differences in weight loss between participants when calories were controlled.
Now that carbohydrates alone are in the clear from being the weight loss devil, what actually does cause weight gain then? There are several things, but I will illustrate just 4 that I believe have the most impact. Starting with the biggest factor of all.
1. Caloric Intake Increase
Source: Dr. Stephan Guyenet. Why Do We Overeat? A Neurobiological Perspective. 2014. (Data from CDC NHANES Surveys and USDA Food disappearance data)
Earlier I mentioned how if carbs were the cause of obesity, then you should be able to see a clear cause-and-effect relationship. Unlike the carb chart shown prior, you can see that the relationship between calories and obesity follow a much clearer trend. As caloric intake (in green) increases, the level of obesity and very obese follow the same trend.
May not seem like anything enlightening to some of you, but there are those who think calories do not matter, cough cough keto-lovers (to be fair, not all of them do).
What we can conclude from examining this chart and the carb chart from earlier is that it is not carbs alone that leads to obesity, but rather an over-consumption of calories from all sources. As mentioned earlier, carbs are part of the equation of excess calories, since they contain calories, but should not be singled-out as the only reason to why obesity occurs.
2. Junk Food
Source: Dr. Stephan Guyent. Fast Food, Weight Gain and Insulin Resistance. Whole Health Source.
Over the last 120 years our eating habits have changed dramatically. We have gone from eating about 95% of our meals from home to roughly only 50%! Thats right, 50% of our meals in today's world are eaten outside of our home. Furthermore, approximately 20% comes from fast food restaurants. It is no secret that eating out provides a larger quantity of calories than you would eat from a home-cooked meal.
What this graph doesn't show, and can only add to the over-consumption of junk food, is the fact that the foods that are eaten at home are a lot more highly processed then they used to be as well. These foods also, typically, are easier to overeat in comparison to whole foods.
3. Fewer calories burned at work
Source: Church TS, et al. Trends over 5 decades in U.S. Occupation-Related Physical Activity and Their Associations with Obesity. PLoS One, 2011.
This graph shows that people are burning roughly 100 calories less per day during work. May not seem like much, but 100 calories per day over the course of the week or month adds up to make a big difference.
What this graph doesn't depict is how much less we move outside of work also. TV shows, Netflix (without the chillin'), sports, there are just infinite things to keep us on the couch and watching TV. This has lead to dramatically less movement, and more screen time. In turn, this means that we burn less calories at work, and also after work.
Putting this chart together with the first caloric intake increase chart, we can see that we eat more calories and burn fewer calories than we used too. Now, this is the recipe for weight gain, not the poor little carbs.
4. Not enough sleep
Our quantity of sleep has decreased by almost 2 full hours over the last several decades. Poor sleep has been associated with obesity. In fact, a meta-analysis study in the journal of sleep examined 45 prior studies and concluded that studies from across the world show a consistent increased risk of obesity for short sleepers. Furthermore, sleep was one of the strongest risk factors for obesity with a 89% increased risk for children, and 55% increased risk for adults!
One of the most well-known reasons to why short-sleep causes over eating is because of the effect it has on our hormones. The two most notable hormones are grehlin and leptin. The former is the hormone that tells us we are hungry, think "growlin grehlin" for your stomach growling when you're hungry, and the ladder is the hormone that controls satiety making us feel full.
Studies show that during times of poor sleep, our ghrelin levels increase (making us feel hungrier), and our leptin levels decrease (making us feel less full). This combination is a perfect hormonal storm to cause overeating.
Making sense of it
Weight gain is a complex issue caused by numerous factors, not just carbohydrate intake. Ultimately, however, these factors lead to the direct cause of obesity- over-consumption of calories.
Carbohydrates have an undeserved and misinterpreted stigma attached to them. In terms of weight loss, a single food or food group can't be isolated as the sole contributor of obesity. Through several general population statistics and clinical trial research, we can learn that carbohydrates, under a caloric restriction diet, makes no significant difference to your weight loss outcome.
This is a crucial for people and for registered dietitians and nutritionist to be aware of. This allows for flexibility in dieting without having to feel overly restricted and guilty. Instead, we can focus on eating foods we enjoy, and setting ourselves up for long-term success by dieting in a way where our number one priority is adherence and consistency, instead of starvation and restriction. Let's learn to follow science instead of what your misinformed friend, news, or instagram/facebook post tells you (unless they're my posts of course!).
I have to go eat my bread, rice, and potatoes now! Have a good day!