10 reasons you’re tired on a plant-based diet & how to fix it

An RD shares 10 reasons you’re tired on a plant-based diet and simple ways to fix each issue, including the best plant-based foods for energy.

One of the most common complaints I hear from plant-based athletes is that they feel tired all the time. Many athletes and fitness enthusiasts switch to a plant-based diet because they think it will give them more energy and make them feel healthier. 

But over time, they start to feel sluggish and fatigued during a workout and throughout the day. What gives? 

Don’t quit on your plant-based diet just yet! Rest assured that this isn’t the norm, and you can most likely fix the issue with slight tweaks to your diet and lifestyle. Let’s examine some of the common culprits for low energy on a plant-based diet and how to fix each issue.

1. You’re not eating enough

Many people transition to a plant-based diet because they want to lose weight. They stop eating animal foods and cut out significantly decrease calories. 

While that sounds great for weight loss, not eating enough calories for your life and activity level can result in low energy levels. Your body needs a certain amount of calories to survive and thrive. 

The number of calories the body needs for basic functions, like breathing, digesting food, pumping blood, etc. is called BMR– basal metabolic rate. 

Everyone’s BMR is different. Here’s how to calculate it: 

• Men: BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) – (5.677 x age in years)
• Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) – (4.330 x age in years)

It’s a bit complicated, so you can also use a BMR calculator. 

On top of that, your body needs calories for daily activities, like walking, doing chores and standing.

And of course, you also need calories for exercise. Not taking in enough calories for all of these functions may result in low energy levels. 

How to fix it:

Eat enough calories to cover your BMR, and then add on for AMR (active metabolic rate. 

Calculate Your AMR:

• Sedentary (little or no exercise): AMR = BMR x 1.2
• Lightly active (exercise 1–3 days/week): AMR = BMR x 1.375
• Moderately active (exercise 3–5 days/week): AMR = BMR x 1.55
• Active (exercise 6–7 days/week): AMR = BMR x 1.725
• Very active (hard exercise 6–7 days/week): AMR = BMR x 1.9

Track calories for a few days to get a sense of how much you’re actually eating to make sure it’s enough.

2. You’re missing out on Vitamin B12

Vitamin B12 is responsible for converting glucose to energy. It’s a vitamin that is made from microorganisms in an animal’s intestines or diet, but humans are not able to make their own Vitamin B12. 

Plants aren’t able to make Vitamin B12, which is why you won’t find much Vitamin B12 in vegan foods. There are some rare instances of fermented foods having natural Vitamin B12 because the bacteria used to make the food produce this vitamin.

That said, many plant-based eaters don’t hit their recommended 2.4 mcg daily intake for Vitamin B12. Without enough Vitamin B12 in the diet, most people feel sluggish and fatigued. 

How to fix it:

If you think you’re deficient in Vitamin B12, ask your doctor to check your levels through a simple blood test. If your levels are low, take a Vitamin B12 supplement. 

And incorporate more plant-based Vitamin B12 foods into your diet.

3. You’re not eating enough iron 

Iron is another nutrient that contributes to energy levels. This mineral transports oxygen throughout the body. Without enough iron in the diet, you may feel fatigued due to lack of oxygen in the muscles.

Iron is a little bit harder to get on a plant-based diet, but it’s not impossible to find. There are two types of iron– heme and non-heme iron. 

Heme iron comes from animal foods and it’s easily absorbed. Non-heme iron comes from plant-based foods and it’s not absorbed as well. The daily recommendation for iron is 18 milligrams, but the National Institute for Healthy (NIH) recommends that vegetarians eat 1.8 times more iron than meat-eaters (or about 32 grams). 

How to fix it: 

If you think you may be iron deficient, ask your doctor to check your blood levels. You do not want to take an iron supplement unless you know you need it. Too much iron in the blood can be toxic. 

It never hurts to add more iron-rich foods to your plant-based diet. Here’s a list of plant-based iron-rich foods. 

Carbs should be the majority of any athlete’s diet. As a matter of fact, 45-65% of the diet should come from carbs. 

4. You’re eating too many carbs

Carbs are not only found in sugary foods, like sodas, desserts and snacks. They are also the most abundant nutrient in fruits, vegetables, whole grains, beans and legumes. 

Some plant-based eaters overdo it on carbs and don’t have enough protein and fat in their diet. If your diet is heavy on grains, beans and legumes and omits soy, nuts and seeds, you may not be eating as much protein as you think. 

This can be a problem because carbs raise your blood sugar, and without protein and fat, that spike in blood sugar is quickly followed by a crash. 

How to fix it:

Protein and fat help even out blood sugar levels, so eating a balance of 45-65%  of calories from carbs with 20-30% calories from protein and 20-30% calories from fat is the right ratio to keep you energized. 

5. You’re not getting enough sleep

This seems obvious, but I throw this in here to remind you that low energy isn’t always from the diet. Most people need 7-8 hours of sleep per night to feel well rested. 

If you’re getting up at 5 or 6am to workout and going to bed at 11pm, you’re probably not sleeping enough. That’s the likely culprit of your low energy levels.

How to fix it:

Make a log of your sleep and wake times for a few days. If you notice that you’re consistently sleeping less than 7 hours per day, try to go to bed an hour earlier. 

6. You’re ignoring recovery nutrition

After a workout, recovery nutrition is important to repair muscles and restore glycogen, but it’s also crucial for energy levels. 

I chat about this on the Greenletes Podcast [listen to the episode here]–in the time following a workout, the body suppresses a certain hormone called ghrelin. This hormone regulates hunger and suppression of it may make you feel less hungry.  This often results in poor recovery nutrition habits. 

But the thing is… your body needs calories and nutrients after a workout to restore its energy levels. You use stored carbs, aka glycogen, for energy during a workout. In addition, muscle tissue breaks down during exercise.

Not to mention that if you don’t eat after a workout, you’ll probably feel very hungry later on in the day. This can cause you to overeat foods that aren’t nutritious and don’t help with recovery.

How to fix it: 

When the workout is complete, you need to replace those carbs so that you have energy for the next workout and take in protein to stimulate muscle growth. Pairing carbohydrates and protein together has been shown to help with overall recovery. [Related: 12 Best Recovery Foods For Vegetarian Athletes].

7. You’re not fueling enough for a workout

If you notice that the fatigue starts to set in during your workout and lasts throughout the day, chances are you’re not eating enough to fuel your activity. The muscles require calories as energy for a workout. 

If you haven’t eaten in a few hours, you’re likely starting your workout with your fuel tank on empty. That means that the body delves into its calorie reserves from glycogen and fat to provide energy for the workout. 

This may sound like it’s okay (who doesn’t want to burn fat?), but this process is taxing on the body and zaps your energy. 

How to fix it: 

Rather than forcing the body to use more energy than it needs, eat a small carbohydrate-rich meal or snack before a workout. 

Here are some of the best pre-workout carb-rich foods. 

8. You’re eating a lot of processed plant-based foods

It’s true that eating plant-based foods are great for your overall nutrition and health, but the types of plant-based foods you choose matter. For example, plant-based whole foods, like fruits, vegetables, beans, legumes and whole grains are rich in vitamins, minerals and antioxidants.

Eating whole foods helps ensure that you get plenty of the aforementioned nutrients, like iron, and Vitamin B12, to keep energy levels high. But processed plant foods, like veggie burgers, snack bars, desserts, chips, drinks and others, usually don’t resemble the plant they came from. 

For example, these cauliflower chips have carbs, calories and sodium, but they are lacking the fiber, vitamins and minerals that are in a head of cauliflower. 

How to fix it: 

Listen to this 5-minute podcast episode about how much processed food to have in your diet. It’s absolutely fine to eat processed foods in moderation, but try not to let more than ⅓ of your diet come from processed foods. 

9. You’re overexercising 

The term “overexercising” is relative and hard to pinpoint. Since everyone exercises different amounts, an excessive amount of activity can be different for everyone. But overexercising is definitely a problem for some people and leads to extreme fatigue.

Some classify overexercise as engaging in more than 2 hours of moderate to vigorous activity everyday or reaching a maximal heart rate on the majority of your workouts. 

When you overxercise, you may feel constantly tired and experience extreme muscle soreness and heavy legs. The body doesn’t have time rest in between workouts and never recovers properly. 

How to fix it:

Although exercising a lot may seem like a good thing, overexercising is doing more hard than good to the body. Take a break and give yourself rest to properly recover. Rest and easy days are crucial to building strength. 

10. You have a medical condition

It’s possible that you may be fatigued due to a medical condition, like an under active thyroid, a nutrient deficiency, Diabetes or another issue. Hopefully this isn’t the case, but you can’t rule it out. It’s better to ask questions about your health than ignore the issue. 

How to fix it:

If you feel like you’re tired all the time, but you’re doing “everything right” in terms of diet, exercise and sleep, talk to your doctor. 

Ask them to do a full blood workup to find the underlying cause. And make sure they listen to your concerns and don’t write it off as too little sleep. Find a doctor that takes the matter seriously.