Determining how many carbs to eat can be one of the most confusing elements of nutrition. After all, humans are biologically driven to seek out carbohydrate-rich foods, which are rewarding, stimulating a release of feel-good neurotransmitters like dopamine. You get basically the same neurochemical response from eating carbs as you do from hearing your phone beep with a new text—and chances are, you know how addicting that can be!
This article will focus on frequently asked questions about carbs to help you overcome the confusion and develop an eating plan so that you optimize body composition, performance, and health.
Question #1: What Are Carbs?
Carbohydrates are one of the three main classes of food, called macronutrients. The other two are protein and fat. We get all of our calories from the macronutrients, while micronutrients in the form of vitamins and minerals provide the rest of our nutritional needs.
Carbohydrates can be found in a wide range of foods: Vegetables, fruit, beans, dairy, seeds, tubers, grains, and processed foods made from these ingredients. Many foods are mixtures: For example, many seeds, legumes, and dairy products contain all three macronutrients, whereas most vegetables, fruits, and grains are primarily carbohydrates, although certain fruits such as avocados and olives are higher in fat.
Question #2: What About Bread, Pasta & Donuts—I Thought Those Were Carbs Too?
One reason carbs can be confusing is there are many different kinds of carbs. Bread, pasta, and donuts fall under the category of refined or processed carbs. Refined carbs are made from grains and other plants, but they are highly processed and stripped of fiber. Many refined carbs have added sugar.
Refined carbs are called “simple” carbs because they are quickly digested due to their lack of intact fiber. Examples of refined carbs include bread, cereal, pasta, sweets, and foods and beverages with added sugar. These foods generally fall under the category of “unhealthy” carbs.
The alternative is whole carbohydrates, which are predominantly plant-based foods that grow in nature and contain fiber. Another name for them is “complex” carbs because they are digested slowly and haven’t had the fiber removed. Examples are vegetables, fruit, grains, tubers, and seeds. These foods generally fall under the category of “healthy” carbs.
There are also dairy products that contain no fiber and require some processing but are often considered beneficial to health. The natural carbohydrate in dairy is lactose, however, some dairy also has added sugar, such as sweetened yogurt or chocolate milk.
Question #3: What Is the Purpose Of Carbs In Human Health?
Carbohydrates are broken down and turned into glucose to provide “energy” for cells in the form of ATP. Many people think that carbs are necessary for energy, but this actually isn’t true. You can produce ATP from both protein and fat, however, the process is faster with carbs. Therefore, if you’re an athlete, or need to quickly replenish energy stores due to fasting or a high activity requirements, carbs are your go-to food source.
Question #4: Do Carbs Cause You To Gain Fat?
You gain fat when you eat more calories than you burn. Carbs by themselves don’t cause this. However, carbs are a source of calories and certain types of carbs stimulate food intake, making it easy to overshoot calorie needs. Refined carbs and those with added sugar are the biggest culprits when it comes to fat gain because they are high in calories and very palatable, making them easy to overeat. When combined with the sedentary lifestyle that is common in modern culture, diets high in refined carbs and added sugar are associated with excess body fat.
Question #5: Do Carbs Cause Type 2 Diabetes?
Although still incompletely understood by scientists, Type 2 Diabetes is believed to be a result of excess body fat and a sedentary lifestyle. It occurs when the body is unable to respond properly to the hormone insulin that is produced by the pancreas. Insulin regulates blood glucose, storing it either as glycogen in muscle or as fat. Carbs don’t directly cause Type 2 Diabetes, however, diets high in refined grains and added sugar are linked with fat gain and they can contribute to problems with insulin, especially when combined with a lack of physical activity.
Question #6: How Many Carbs Should I Eat Per Day?
There is no universal answer to this question. Optimal carb intake will depend on multiple factors including activity levels, goals, preference, age, and metabolic status. That said, here are some general recommendations:
For Fat Loss: Although it’s possible to lose body fat with a high-carb, low-fat diet, low-carb diets are very effective for producing short-term fat loss because they reduce appetite. The following carb recommendations are for foods other than low-carb vegetables, such as leafy greens and broccoli.
For sedentary individuals with a lot of weight to lose, less than 50 grams of carbs a day is recommended because this will improve the body’s ability to burn fat.
For active people who are overweight, 50 to 100 grams of carbs tend to be the sweet spot. Wondering what qualifies as “active?” One example would be if you exercise with weights three times a week and do a brisk 30-minute walk on off days.
For the very active who train hard but want to lose fat, anywhere from 100 to 300 grams a day could be indicated. Most people will likely get the best body composition changes form around 150 grams a day.
Carb cycling may be ideal for people who train hard: Go higher in carbs on training days (anywhere from 100 to 300 grams, depending on multiple factors) and lower on recovery days (anywhere from 50 to 100 grams).
For Diabetes/Prediabetes/Metabolic Syndrome: For this population, a lower carb diet that prioritizes whole foods is generally indicated to restore insulin sensitivity and improve glucose tolerance. It will also encourage fat loss, which is generally a priority for this population. Under 50 grams of carbs a day is generally indicated, although individual need will vary. For example, in certain situations, such as diabetes with a lot of inflammation, a plant-based diet that has a higher intake of carbohydrates (from whole sources) may be beneficial.
For Lean, Fit, Healthy Individuals: If you’re lean and healthy but not a hardcore trainee, your carb needs will be relatively high. A general rule is up to 3g/kg of body weight, so if you weigh 165 lbs or 75 kg, you may benefit from as much as 225 grams of carbs. Best results will come from prioritizing whole carb sources.
For Athletes & People Trying To Put On Muscle: Strength and power athletes who rely on the glycolytic energy system for a large portion of their training generally benefit from above 3g/kg of carbs a day. One review recommended a range of 4 to 7 g/kg for athletes. A high-carb intake will improve hormonal balance and restore the glycogen energy source in muscle, supporting recovery.
Question #7: What Is the Ideal Timing For Carb Intake?
Timing your carb intake is one of the lesser known tricks for getting body composition and performance (both mental and physical) results. Unfortunately, there is a lot of misinformation when it comes to carb timing, from the belief that carbs eaten at night are stored as fat to the idea that a high-carb breakfast of juice and cereal or toast will provide “energy” for the day.
Why does carb timing matter?
First, willpower is generally at a high point in the morning. For people on lower carb programs, saving carbs for later in the day plays to this advantage, while allowing you to enjoy carbs when your mental resources are reduced.
Second, carbohydrates raise insulin and blood sugar, while also affecting other energy-related messengers in the body. Consuming high-carb foods, especially the refined carbs that constitute most traditional breakfast foods, in the morning is not recommended because it has a sedating effect. In contrast, eating carbs at dinner will lower the stress hormone cortisol and raise the relaxing feel-good neurotransmitter serotonin so you can unwind and get a restful night’s sleep.
Third, shifting carbs to the evening/post-workout allows you to prioritize protein and fat at breakfast, which sets up your neurotransmitters for a productive, energy-filled day.
Finally, for athletes or people who train hard and often, carbs are necessary after exercise to replenish the energy stores in the muscle and they can enable better cognitive function in certain situations.
Question #8: What Is A Healthy Amount of Carbs At Night For Someone On A Low-Carb Diet?
A common problem with fat loss programs is that nutrition falls apart and people overdo carbs at night. As with every carb-related recommendation, individual carb timing will depend on your situation. For fat loss and treating metabolic problems, the general recommendation for carb intake will be around 50 to 60 grams a day. Split your carbs between post-workout and dinner. You could have 30 grams of higher carb foods after training and the same amount at dinner for a total of 60 grams of carbs. This doesn't include low-carb vegetables like leafy greens.
Examples of a serving of carbs equaling roughly 30 grams is half a sweet potato, half a cup of quinoa, an apple or a banana. Some people prefer to have all their carbs at once because this means they get a larger portion, in which case, time them whenever you enjoy them most.
If you have a higher daily carb intake (100 to 150 grams), you might decide to have two servings of carbs at dinner (60 to 80 grams) and the rest post-workout. Or you could split your carb needs over lunch, dinner, and post-workout. The key is to avoid going off the rails on carbs at night because this often leads to overeating and a calorie surplus so that you gain fat.
Question #9: How Does Age Impact Carb Needs?
If you’re like a lot of people, you never had to worry about carbs as a kid, but now as you are getting older, you wonder if you might be overshooting your carb needs. In fact, aging coincides with a decrease in insulin sensitivity, and for many people, a reduction in carb requirements.
As people get older, they become less active, tend to perform less heavy lifting, and lose muscle mass. Every muscle cell has insulin receptor sites, so as muscle is lost, insulin receptor sites disappear. Additionally, mitochondria, which are the energy factories in the cells, become dysfunctional, which leads to a drop in the cell’s ability to bind with insulin. Another reason carb intake needs to be moderated with aging is that high glucose levels are associated with high blood pressure and decreased flexibility of blood vessels, which increases cardiovascular disease risk.
Individual carb requirements will vary in older adults depending on physical activity and exercise status, disease state, and body composition, but a general recommendation is to focus on getting your carbs from quality, high-fiber sources like vegetables, legumes, and fruit because these foods provide phytonutrients that improve insulin sensitivity, while helping to eradicate inflammation that increases with aging.
Question #10: Doesn’t The Brain Require 130 G Carbs A Day To Function?
A favorite argument of detractors of low-carb diets is that they don’t provide sufficient glucose for the brain. Fortunately, this is not true. Just think how much trouble our hunter-gatherer ancestors would have been in if brain function was compromised every time carbs were scarce. A daily intake of 130 grams of carbs a day is no small feat when you don’t have a local grocery store stocked with fruit, bread, cereal, grains, and chips for your convenience.
Here’s the truth: The brain does require about 50 grams of glucose a day, but this doesn’t need to come from dietary carbs. Rather, the liver is capable of supplying the brain’s glucose needs via a process known as gluconeogenesis in which it uses energy substrates like glycerol, lactate, and pyruvate. The remaining energy needs for the brain can be derived from ketones, a byproduct of fat metabolism.
Having the brain get energy from ketones improves brain function and is the reason that ketogenic diets are used to treat brain disorders. Having the brain run on ketones may also have an anti-aging effect, protecting the brain from cognitive impairment and Alzheimer’s.
It should be noted that the body requires a 1- to 2-week adaptation period to be able to utilize ketones effectively. Don’t worry—your brain won’t stop working but you may experience some brain fog and reduced cognition while your metabolic machinery gets up to par. It’s worth going through the adaptation period because it makes your body metabolically flexible and means you are no longer a slave to carbs.