1. Carbs Are Not Uniquely Fattening
Scientists once hypothesized that carbs increased the risk of obesity more than fat and protein.
According to this hypothesis, carbs are the primary cause of obesity due to their ability to raise insulin levels, which in turn promotes the storage of calories as fat. This idea is known as the carbohydrate-insulin model of obesity.
Of course, excessive intake of any calorie-providing nutrient — fat, carb, or protein — is an effective recipe for weight gain and obesity.
But no compelling evidence supports the idea that high-carb diets are especially fattening. In fact, many studies suggest that there is no significant association between high carb intake and obesity.
Nevertheless, healthy low-carb diets have been proven effective for weight loss — at least in the short term.
Scientists believe that their effectiveness is due to the elimination of refined carbs like sugar and an increased focus on healthy, high-fiber carb sources, as well as protein and fat.
Still, one large, 12-month study that compared the effectiveness of a healthy low-carb diet with a healthy low-fat diet detected no significant differences in weight loss.
In short, the quality of the carbs you eat is of greater importance than the proportion of carbs in your diet.
Thus, you should avoid eating a lot of sugar and other refined carbs, and instead focus on whole, carb-rich foods like fruits, vegetables, roots, and tubers.
SUMMARY Carbs don’t cause weight gain unless they contribute to excessive calorie intake. Carb quality is of greater importance. Avoid unhealthy, refined carbs and focus instead on healthy, high-fiber carb sources.
2. Early Humans Frequently Ate Carbs
Learning to cook was a game-changer for early humans, as cooked meat provided increased protein, fat, and calories.
Yet, new evidence indicates that carb-rich foods like root vegetables, legumes, and even grains were cooked and consumed by human ancestors as well.
Cooked carbs would not only have been more nutritious but also more appealing to a hungry hunter-gatherer.
This theory is supported by emerging biological evidence showing that early humans began developing extra copies of the amylase gene, which helps produce the enzymes you need to digest starchy carbs.
In fact, this change in DNA occurred long before humans started farming.
That's why people today can have up to 18 amylase gene copies, indicating that humans have evolved to digest starches more efficiently.
Also, consider that every single cell in your body runs on glucose, which is a carbohydrate sugar. Even the most fat-adapted brain requires at least 20% of its energy from carbs.
SUMMARY Genetics and archaeological evidence suggest that humans ate high-carb foods long before they started farming.
3. Gluten Intolerance Affects Few People
Gluten is a protein found in wheat, barley, and rye. By cutting carbs from your diet, you automatically cut out gluten, too.
A gluten-free diet is necessary for the small number of people with celiac disease or some other types of autoimmune disease.
Gluten-free diets may also benefit people with non-celiac gluten sensitivity or wheat intolerance.
However, studies indicate that few people with self-reported gluten sensitivity have this condition at all. One study showed that only 3 out of 59 participants who believed they were gluten sensitive reacted to gluten.
New research strongly suggests that the condition known as non-celiac gluten sensitivity is not sensitivity to gluten at all.
Instead, it appears to be sensitivity to fructan, a type of soluble fiber or FODMAPs found in wheat.
FODMAPs like fructans cause digestive symptoms like gas, diarrhea, and stomach pain in some people — especially those with irritable bowel syndrome (IBS).
If you have FODMAPs sensitivity, there is no reason for you to avoid carbs altogether. Instead, try to identify and avoid only those foods to which you’re sensitive.
SUMMARY Though removing gluten is crucial for some people, current evidence suggests that most people don't benefit from a gluten-free diet.
4. Fiber — a Carbohydrate — Is Important for Optimal Health
Nutrition is rarely black and white.
Still, most experts agree that eating fiber is good for your health.
In particular, soluble fiber is known to benefit heart health and weight management.
The thick and sticky soluble fiber found in high-carb foods like legumes, fruits, and oats helps slow down digestion.
Fiber also increases the time it takes to digest and absorb nutrients, contributing to reduced body weight and improved health.
SUMMARY Most dietary fiber is made of carbohydrates. Soluble fiber is particularly beneficial for weight maintenance and heart health.
5. Gut Bacteria Rely on Carbs for Energy
The balance between beneficial and harmful gut bacteria may influence your risk for many lifestyle diseases, both physical and psychological.
To grow, your beneficial gut bacteria need carbs that they can ferment for energy.
As it turns out, soluble fiber appears to be the important nutrient they feed on.
Once again, some of the best food sources of soluble fiber include legumes and oats, which are high in carbs.
SUMMARY Eating soluble fiber may play a crucial role in maintaining a healthy balance of gut bacteria.
6. Legumes Are a Superfood — on a Nutrient-To-Cost Basis
Legumes are edible plant seeds that include beans, peas, chickpeas, lentils, and peanuts.
They’re naturally high in carbs and thus often excluded from low-carb eating patterns. They’re also eliminated on a strict paleo diet.
However, legumes are nutritionally unique.
They’re one of the few foods rich in both protein and fiber. Legumes are also high in vitamins and minerals. Plus, calorie for calorie, they’re one of the most nutrient-dense foods available.
Additionally, they’re very cheap to produce and package compared to other high-protein food sources like meat and dairy.
This remarkable nutrition-to-cost ratio is why legumes are an important food staple in many developing countries.
SUMMARY Legumes are incredibly healthy and amazingly cheap. They’re rich in protein, fiber, and other valuable nutrients. Calorie for calorie, they’re one of the most nutritious foods.
7. Cutting Carbs Does Not Improve Exercise Performance
It’s a myth that a low-carb diet can outperform a conventional high-carb diet for athletes.
In a well-designed study in cyclists performing a 62-mile (100-km) trial with intermittent sprints, participants followed either a low-carb or a high-carb diet for the week leading up to the test.
Though both groups had similar race times, the high-carb group outperformed the low-carb group's sprint output on all four occasions.
While a single study is insufficient to draw solid conclusions, the weight of evidence overwhelmingly supports these results.
If you're fat-adapted on a low-carb diet, you can still perform very well, but no high-quality studies show that cutting carbs allows you to outperform those on higher-carb diets.
This holds true for cardio endurance events like cycling, as well as weight training and bodybuilding for muscular strength and endurance.
For those who simply exercise to keep fit, a low-carb diet will likely not have a negative impact on your performance — but it probably won't improve it either.
SUMMARY Athletes don’t perform better on low-carb diets than higher-carb ones. Performance is similar for endurance but worse for sprinting if you’ve cut down on carbs.
8. Carbs Don't Cause Brain Damage
Some claim that carbs cause harmful brain inflammation. However, this idea is not based on scientific evidence.
Unlike refined grains, whole grains are high in magnesium and fiber — both of which are linked to less inflammation.
In fact, the extensively studied Mediterranean diet, which is rich in whole grains, is strongly associated with slower age-related mental decline and a lower risk of Alzheimer's disease.
On the other hand, high intake of refined carbs and added sugar should be avoided. As part of an unhealthy lifestyle, these ingredients reduce overall health, adversely affecting your body as a whole.
SUMMARY There is no evidence linking whole carb sources to brain damage or diseases like Alzheimer's. In fact, the Mediterranean diet, which is rich in whole grains, is linked to improved brain health.
9. The World's Longest-Lived Populations Eat Plenty of Carbs
The Blue Zones — the regions where people live measurably longer — provide scientists with unique insights into certain eating patterns.
The island of Okinawa in Japan has the most centenarians (people who live over the age of 100) in the world.
Their diet is very high in carb-rich sweet potatoes, green vegetables, and legumes. Prior to 1950, a whopping 69% of their calorie intake came from sweet potatoes alone.
Another long-living population inhabits the Greek island of Ikaria. Nearly 1 in every 3 people lives to be 90, and they eat a diet rich in legumes, potatoes, and bread.
Several other Blue Zone regions share similar dietary traits, indicating that carbs are not causing problems for these people.
SUMMARY Some of the world's longest-living populations eat diets with plenty of high-carb plant foods.
The Bottom Line
It's important to think about foods as a whole and not just consider their individual nutrients. This is especially true when it comes to carbs.
For instance, carb-laden junk foods are unhealthy, providing no nutritional value. They’re today's biggest contributors to excess calories.
And though low-carb diets can be an effective tool for weight loss and diabetes control, that doesn't mean carbs alone cause weight gain or disease — nor are they the sole cause of the current state of public health.
This depends entirely on the context and varies between individuals.
Some people do well with fewer carbs, while others function just fine eating plenty of carbs from healthy food.
In any case, whole-carb foods can be part of a healthy diet and don’t need to be avoided at all cost.