Why many people feel tired after going vegan—and how to fix it naturally

Adopting a plant‑based diet can feel like a glow‑up—lighter meals, smaller grocery bills, a happier planet.

Yet a surprising number of new vegans report the opposite at first: heavy eyelids, afternoon crashes, workouts that suddenly drag. If that’s you, take heart.

Feeling drained rarely means veganism “isn’t for you” — it usually means a few nutrients slipped through the cracks when you ditched animal foods.

Below is a step‑by‑step troubleshooting guide.

For each energy gap, you’ll see why it happens, how to spot it, and practical fixes you can put into motion today—no complicated meal plans, just beginner‑friendly tweaks grounded in nutrition science.

Step 1: Make sure you’re eating enough calories

Plant foods tend to be less calorie-dense than cheese, meat, or butter.

Swap a 300-calorie chicken breast for a 110-calorie cup of black beans without adding extra grain or fat, and you’ve created an energy deficit. Chronic under-fueling forces your body to conserve resources — fatigue is the first red flag.

Quick checks

• Weight loss you didn’t plan

• Brain fog or crankiness near meal time

• An afternoon slump even after decent sleep

Fix it naturally

1. Add calorie‑dense whole foods at each meal: half an avocado, a spoonful of peanut or almond butter, a drizzle of olive or flax oil on roasted veggies.

2. Batch‑cook a grain base (quinoa, brown rice, farro). Scoop a cup under soups and salads for an effortless 200–250 calories plus slow carbs for energy.

3. Top salads like you mean it: hemp hearts, toasted sunflower seeds, olives, and dried fruit turn a bowl of greens into a 600‑calorie powerhouse that still feels light.

Step 2: Check your vitamin B12 intake

B12 keeps red blood cells healthy and nerves firing.

Plants don’t make it — animals accumulate it from bacteria. Go vegan without a B12 game plan and stores will run low in months, sometimes weeks.

Low B12 equals anemia, numbness, and—you guessed it—fatigue.

Quick checks

• Tingling in hands or feet

• Pale skin or tongue

• Lab test: serum B12 below 220 pg/mL or elevated homocysteine

Fix it naturally

1. Use fortified staples—nutritional yeast, plant milks, and some breakfast cereals. Two tablespoons of fortified “nooch” dusted on popcorn can deliver 100% of the daily value.

2. Take a micro‑dose supplement: 25–100 mcg daily chewable or 1,000 mcg weekly. Both are inexpensive and vegan.

3. Set a hygiene rule: Put B12 tablets next to your toothbrush so it becomes automatic.

Step 3: Optimize iron absorption

Plants provide non-heme iron, which the body absorbs at 5–12%, versus 15–35% for heme iron from meat.

Low iron saps hemoglobin, starving muscles and brain cells of oxygen.

Quick checks

• Cold hands and feet

• Shortness of breath on stairs

• Lab test: ferritin below 30 ng/mL

Fix it naturally

1. Pair iron with vitamin C. Sprinkle lemon juice on sautéed spinach; add bell‑pepper strips to hummus wraps; drink a small glass of OJ with your bean chili. Vitamin C can triple non‑heme iron absorption.

2. Mind the iron blockers: coffee, black tea, and calcium supplements inhibit uptake when consumed with iron‑rich meals. Enjoy them an hour apart.

3. Iron‑rich vegan MVPs (per cup cooked): lentils 6.6 mg, kidney beans 5 mg, tofu 6.6 mg. Combine two per day and you’re close to the 18 mg RDA for pre‑menopausal women.

Step 4: Balance omega‑3 fatty acids

ALA (alpha‑linolenic acid) from plants converts inefficiently to EPA/DHA, the forms that quell inflammation and support brain function. Skimp and you may feel foggy or fatigued.

Quick checks

• Dry skin, brittle nails

• Achy joints not explained by exercise

• Mood dips that accompany tiredness

Fix it naturally

1. Daily seed ritual: 2 Tbsp ground flax or chia in oatmeal or smoothies gives ~3 g ALA.

2. Walnut swap: trade almond snacks twice a week for walnuts to diversify fatty acids.

3. Consider algae oil: 250–500 mg DHA/EPA a few times a week covers bases if you’re highly active or pregnant.

Step 5: Shore up iodine and selenium

Both minerals support thyroid hormones that regulate metabolism. Dairy and seafood used to supply them.

However, vegan newcomers sometimes forget replacements.

Quick checks

• Persistent low energy even after addressing calories and iron

• Dry skin and mild weight gain

• Lab test: TSH creeping above 3 mIU/L

Fix it naturally

1. Use iodized salt, not fancy sea salt, in home cooking—just ¼ tsp meets the 150 mcg daily target.

2. Seaweed once or twice a week—a small sushi nori sheet supplies ~25–45 mcg iodine.

3. Brazil‑nut trick for selenium: one or two nuts a day (no more; selenium can be toxic in high doses) meet the 55 mcg requirement.

Step 6: Upgrade protein distribution

You can meet total protein needs, yet still feel sluggish if intake clusters in one meal. Muscles rebuild throughout the day. Therefore, spreading protein helps stabilize energy and blood sugar.

Quick checks

• 20 g protein dinner, 3 g breakfast pattern

• Post‑lunch lethargy despite enough calories

Fix it naturally

1. Front‑load breakfast: tofu scramble on whole‑grain toast or soy‑yogurt with hemp and fruit gives 15–20 g right away.

2. Portable pulses: keep roasted chickpeas or edamame in your bag for a 7–8 g boost mid‑morning.

3. Even‑split strategy: aim for ~15 g protein at each of three meals plus two 7‑g snacks; that’s 61 g—a solid target for many adults.

Step 7: Hydrate and mineralize

Higher-fiber vegan diets increase water needs. Dehydration masquerades as fatigue and hinders nutrient transport.

Quick checks

• Dark urine after noon

• Heavy legs during light workouts

Fix it naturally

1. Set a ½‑body‑weight rule: drink in ounces half your body‑weight, more if you exercise.

2. Add citrus or mint to water for a micro‑dose of electrolytes and flavor.

3. Broth boost: sip a mug of miso or vegetable broth mid‑afternoon; the sodium and potassium perk you up more gently than caffeine.

Step 8: Diversify B‑vitamins through fermented foods

B6, B2, and folate convert food to energy; deficiencies sap stamina.

Fermented foods often pack extra B vitamins thanks to microbial synthesis.

Quick checks

• Glossitis (smooth tongue)

• Low mood plus tiredness

Fix it naturally

1. Kimchi or sauerkraut: a forkful with lunch.

2. Miso, tempeh, or natto: fermented soy products deliver B2 and K2.

3. Sourdough bread: whole-grain sourdough can increase folate availability vs. non-fermented loaves.

Step 9: Limit ultra‑processed vegan stand‑ins

Packaged mock meats and sugary vegan treats often lack fiber and micronutrients yet still contain refined carbs or additives that cause energy crashes.

Quick checks

• Feel fine until a faux‑burger lunch, then sluggish by 2 p.m.

• Reliance on packaged bars instead of fruit or nuts

Fix it naturally

1. Follow a 3‑ingredient rule: if a vegan snack lists more than three sweeteners or gum stabilizers, treat it as an occasional indulgence.

2. One fresh swap per day: replace a packaged bar with an apple plus peanut butter or a banana rolled in chia seeds.

3. DIY patties: blend beans, oats, and spices—freeze them so you have quick, whole‑food burger options.

Step 10: Track, tweak, triumph

Fatigue can stem from multiple small gaps. A one-week food log reveals patterns you can’t see meal by meal.

Quick checks

• Use any free app or a notebook; note time, foods, mood, and energy level.

Fix it naturally

1. Highlight low‑protein meals; plug them with hemp seeds or a side of beans.

2. Spot long gaps without calories; add a balanced snack.

3. Celebrate wins: more greens? Better hydration? Momentum fuels consistency.

Putting it all together

Imagine tomorrow morning: you sit down to a savory tofu scramble tossed with spinach and red peppers, avocado slices on the side, and whole‑grain toast brushed with olive oil.

Lunch is a vibrant lentil‑quinoa salad with oranges, pumpkin seeds, and a citrus‑tahini dressing. Mid‑afternoon, you crunch roasted edamame while sipping minty water.

Dinner brings a chickpea‑sweet‑potato curry over brown rice, finished with a squeeze of lime. You top off the evening with two Brazil nuts and a mug of ginger‑lemon tea.

That sample day covers calories, B12 (fortified nutritional yeast in the scramble), iron (lentils + vitamin C–rich orange), omega‑3s (flax in the toast), iodine (iodized salt in curry), selenium (Brazil nuts), and hydration.

Energy crash?

Unlikely. And no fancy powders or pay‑walled meal plans—just whole, plant foods in strategic balance.

Most new vegans who tackle fatigue this way report brighter mornings within a fortnight and sturdier workouts in six weeks.

Remember: exhaustion isn’t betrayal by plant foods — it’s your body waving a flag for better balance.

Answer with these natural tweaks, and the glow‑up you imagined when you first went vegan becomes the everyday reality.