Picture of pasta, oranges, potatoes, oats in the background. Do Carbs Make You Tired? Veg Out With Maria

Can Carbs Make You Tired?

Those pesky carbs are at it again. Have you ever eaten a high-carbohydrate meal and then feel like falling asleep afterward? Well, you’re not alone.

Carbohydrates are a vital energy source. However, the type and quality of carbohydrates you eat not only influence your energy levels but your overall health as well.

Before you kick carbs to the curb, let’s give them a chance by reviewing some basics about this important macronutrient. We’ll cover what are carbohydrates, the different types of carbs, how they impact your body, and which carbs to eat for better energy and health.

What are Carbohydrates?

Carbohydrates are one of the three macronutrients essential for the human body, alongside proteins and fats. They are organic compounds composed of carbon, hydrogen, and oxygen atoms, and they serve as your body’s primary source of energy. Carbohydrates can be classified into three main types based on their chemical structure:

  1. Simple Carbohydrates (Sugars): These are composed of one or two sugar units. Examples include glucose, fructose (found in fruits), and sucrose (table sugar).
  2. Complex Carbohydrates (Starches and Fibers): These consist of long chains of sugar molecules. Starches, found in foods like grains and legumes, are a complex form that the body breaks down into simpler sugars for energy. Fiber, another form of complex carbohydrate, is not fully digestible and plays a crucial role in digestive health.
  3. Dietary Fiber: Although technically a complex carbohydrate, dietary fiber deserves special mention. It includes non-digestible plant components that contribute to digestive health, regulate blood sugar levels, and provide a feeling of fullness.

How the Body Converts Carbs into Energy

When you eat carbohydrates your body digests and breaks it down into glucose. The small intestine absorbs these sugar molecules, and from there they enter the bloodstream. The bloodstream then carries glucose to cells throughout your body.

Your cells take in glucose from the bloodstream with the help of insulin, a hormone produced by the pancreas. Inside the cells, glucose undergoes a series of chemical reactions that produce ATP, the energy currency that powers muscle contraction, cellular maintenance, and other essential functions of the body.

3 Main Reasons Why Carbs Can Make You Tired

Eating a large meal or too much of anything can make you tired. During digestion, most of your blood flow goes to the gut and away from your brain and other parts of your body leading to a feeling of fatigue.

There can be different reasons why eating carbs could potentially make you feel tired, but the three main reasons I see are:

1. Eating Too Many Simple Carbs (Refined Carbohydrates)

Eating too many simple or refined carbohydrates can lead to fatigue due to the rapid fluctuations in blood sugar levels and insulin response. Not all carbohydrates are created equal!

Refined carbohydrates include processed cereals with added sugars, sugary drinks, pastries, cookies, cakes, white bread, pasta, and white rice. When you eat these types of carbs, your body rapidly digests and absorbs these into your bloodstream because they contain very little fiber and nutrients.

This quick spike in blood sugar levels causes the pancreas to release insulin. Insulin helps your cells, especially in the liver and the muscles take up glucose from the bloodstream. Insulin gets a bad rap but it’s actually the good guy! We wouldn’t survive without insulin.


  • Swap refined carbohydrates for more “complex” carbs like whole grains, fruits, vegetables, and legumes which are rich in fiber and vitamins and minerals.
  • Look at “Added Sugars” on the nutrition facts label and try to cut back on your overall intake. The American Heart Association recommends limiting added sugars to no more than 25g for women and 36g for men daily.
  • Also, making sure you are eating balanced meals that contain not only healthy complex carbs but also a concentrated protein source along with healthy fat will avoid those “spikes” and support better blood sugar control. For more on eating balanced meals refer to our Supplement & Micronutrient Guide.
Instead of refined carbs and added sugars for breakfast choose whole grains without added sugar and add healthy fats, fruit, and protein to balance it. Veg Out With Maria.

2. Insulin Resistance

As previously mentioned, insulin is a hormone released from your pancreas that signals your cells that there is glucose in the blood. It basically knocks on the cell’s door asking if there’s room to let more sugar in to convert it to energy.

Insulin resistance happens when the cells in your muscles, fat, and liver don’t respond well to insulin and can’t efficiently take up glucose from your blood. Your pancreas responds to this build-up of glucose in your blood by pumping out more insulin to try to compensate.

When your cells become chronically resistant to insulin, this leads to high blood sugar levels which makes you feel very tired and over time causes diabetes and other chronic diseases. Insulin resistance is usually blamed on carbs, however, there is more to the picture than most realize.

We don’t typically associate fat intake with insulin resistance, but there is a proven direct correlation1,2,3. Excessive intake of calories and fat eventually causes inflammation in the adipose (fat) cells which can no longer handle the excess fat.

Your liver and skeletal muscles end up taking on the excess fatty acids, however, these organs are not equipped to store a lot of fat. This is the process of lipotoxicity which is one of the main contributing factors to insulin resistance.

You may notice high blood sugar levels or feeling fatigued after eating only a small amount of carbohydrates. This may be a sign that you are already experiencing insulin resistance. Once you modify your diet and inflammation and insulin sensitivity improve, you will notice that you can tolerate eating more carbs without the symptoms that you were experiencing before.

women looking at food labels at the grocery store


  • Be mindful of your total fat intake, especially saturated fat. The general recommendation is to keep your fat intake to around 25-30% of your total caloric intake. So, if you’re eating 2,000 calories a day, that looks like 56-67g of total fat daily. The American Heart Association recommends aiming to keep saturated fat to no more than 5-6% of your total calories which would be around 13g of saturated fat. Start looking at the Nutrition Facts Label. You will be surprised how much fat you are getting in your prepackaged foods. For more information about saturated fat sources and healthy plant-based fats refer to the blog: The Best Vegan Healthy Fats.
  • Continue to swap out refined carbs for more “complex” carbs.
  • Increase physical movement. You don’t have to do hard-core hour-long cross-fit classes to get benefits. Just moving more, taking the stairs, walking after meals will have a positive impact on your blood sugar levels and how you feel.

3. Not Getting Enough Sleep

Say what? I know it’s a no-brainer to realize that lack of sleep will make you tired, but you may not know that it also has an impact on your blood sugar levels and cravings for refined carbohydrates and energy-dense foods like doughnuts, pizza, chips, and cookies.

Sleep loss has been found to produce marked changes in the secretion of growth hormone and levels of noradrenaline – which can increase circulating fatty acids causing a significant decline in the ability of insulin to do its job4,5.

Studies show that even one night of sleep deprivation can change the levels of your hunger and appetite hormones, leading to increased hunger. Poor sleep also disrupts our endocannabinoid system, responsible for regulating immune response, appetite, and metabolism6.

This can make you crave fatty, starchy and sugary foods which in turn affect your blood sugar levels and insulin response, causing more fatigue.


  • Make sleep a priority. Here are a few essentials: 1.) Keep a regular sleep schedule. Go to bed at the same time each night, and get up at the same time each day, 2.) Avoid screen time before bed. The blue and green light emitted by TVs, smartphones, laptops and tablets negatively impacts your circadian rhythm (your body’s internal clock), 3.) Sleep in a dark, cool environment, 4.) If you can, get outside during the day to get at least 15 minutes of sun. This increases your body’s melatonin production.
woman sleeping well in bed. Sleep, carbs and energy levels. Veg Out With Maria

Carbs & Tryptophan

You may have heard that eating carbohydrate-rich foods increases the amino acid tryptophan in the brain which releases serotonin, some of which converts to melatonin – and there you have it! Sleepiness.

While it is true that meals consisting of mostly carbohydrates (especially high-glycemic index/refined carbs) increase the availability of tryptophan synthesis in the brain (and consequently serotonin), a small amount of protein in the meal blocks this mechanism making it a not-so-common response 7,8.

So, if you are eating balanced meals that include protein and more complex carbohydrates than refined ones, I wouldn’t stress about it!


The main takeaway I want you to get from this is that carbs are not your enemy! The distinction between simple and complex carbs is vital, as excessive intake of refined carbohydrates and excessive fat/saturated fat intake can lead to energy fluctuations, blood sugar imbalances, and subsequent fatigue.

By opting for nutrient-dense, complex carbohydrates found in whole grains, legumes, fruits, and vegetables, and including protein-rich sources for more balanced meals, you can promote stable energy levels, support overall health, and reduce the risk of fatigue.

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