Can Eating Less Meat Make You Tired? Understanding the Nutritional Shift

October 28, 2025 •

3 min read

A systematic review found that while vegetarians often have sufficient total iron intake, their iron stores (ferritin) can be lower than meat-eaters. Therefore, if you're transitioning to a diet with less animal protein, you may wonder: can eating less meat make you tired?

Quick Summary

Reducing meat intake can lead to fatigue primarily due to potential deficiencies in key nutrients like iron and vitamin B12, which are abundant in animal products. Strategically planning meals, consuming fortified foods, and pairing iron-rich plants with vitamin C are key strategies to maintain energy.

Key Points

Iron and B12 are Key: Insufficient intake of iron and vitamin B12 are the most common causes of fatigue when reducing meat, as these nutrients are highly concentrated and bioavailable in animal products.
Enhance Absorption: Maximize non-heme iron absorption from plant sources like lentils and leafy greens by combining them with vitamin C-rich foods such as bell peppers or citrus fruits.
Prioritize B12 Supplements: Because plant foods do not naturally contain B12, regular supplementation or consistent consumption of fortified foods is critical for preventing fatigue and other deficiency symptoms.
Increase Calorie Density: Add healthy, calorie-dense foods like nuts, seeds, and avocados to your diet to compensate for the lower energy density of many plant-based meals and avoid unintentional calorie restriction.
Combine Proteins Strategically: Ensure a complete amino acid profile by combining different plant protein sources, like grains and legumes, throughout the day.
Monitor Your Health: If fatigue persists, consult a healthcare professional to check your iron and B12 levels. This can rule out deficiencies and other health issues.

The Connection Between Less Meat and Fatigue

Reducing meat intake can sometimes lead to fatigue, often as a temporary adjustment. Animal products are rich in certain nutrients essential for energy. Removing them without careful planning can create nutrient gaps, leading to tiredness. However, a well-planned plant-based or flexitarian diet can support or even enhance energy levels. It's vital to identify which nutrients need attention and how to source them from non-meat foods.

Why Fatigue Happens on a Low-Meat Diet

Meat is a convenient source of nutrients. When reduced, the body must adapt to new dietary patterns, which can be challenging without proper nutritional knowledge. Lower energy density in many plant foods means new vegetarians or vegans might consume fewer calories, leading to a deficit and fatigue. The bioavailability of nutrients from plant sources can also differ from animal sources, requiring careful meal planning.

Common Nutritional Gaps and Their Impact

Key nutrients to monitor when eating less meat include iron and vitamin B12.

Iron Deficiency

Iron is vital for oxygen transport via hemoglobin. Deficiency can cause iron-deficiency anemia and fatigue.

Heme vs. Non-Heme Iron: Meat contains more absorbable heme iron. Plant foods have less bioavailable non-heme iron.
Absorption Inhibitors: Phytates in grains/legumes and tannins in tea/coffee can hinder non-heme iron absorption.

Vitamin B12 Concerns

Vitamin B12 is crucial for nerve function and red blood cell production. It's primarily in animal products, making those eating less meat, especially vegans, vulnerable to deficiency.

Severe Symptoms: Deficiency can lead to anemia, nerve damage, and cognitive issues.
Monitoring is Key: Blood tests are necessary to assess B12 status.

Inadequate Protein and Calories

Low protein intake can cause fatigue and muscle weakness. Under-eating due to lower calorie density of plant foods can also lead to feeling drained.

Strategies to Maintain Energy

A well-planned approach can help you maintain energy with less meat.

Fortification and Supplements

Vitamin B12: Consume fortified foods or supplements, especially for strict plant-based diets.
Vitamin D: Fortified foods and supplements are often needed, particularly with limited sun exposure.
Other Minerals: Consider fortified foods or supplements for zinc, calcium, and iodine if needed.

Enhance Nutrient Absorption

Boost Iron Absorption: Pair plant-based iron sources with vitamin C-rich foods.
Limit Inhibitors: Avoid drinking coffee and tea with meals. Soaking, sprouting, or fermenting can reduce phytates. Cooking in cast-iron can increase food's iron content.

Increase Calorie and Protein Intake

Add Calorie-Dense Plants: Include nuts, seeds, avocados, and whole grains.
Increase Portion Sizes: You may need larger portions of plant foods.
Diversify Protein Sources: Combine plant proteins throughout the day to get all essential amino acids.

Crafting a Balanced Plant-Forward Diet

A gradual transition to eating less meat is often easier. Focus on whole foods and a varied diet for a wide range of nutrients. Consult a registered dietitian for personalized advice.

Nutrient Comparison: Meat-Based vs. Plant-Based


Nutrient	Meat-Based Diet (Examples)	Plant-Based Diet (Key Sources)	Notes
Heme Iron	High, easily absorbed (red meat)	None	Focus on absorption enhancers for non-heme iron.
Non-Heme Iron	Present (animal's diet)	High (lentils, spinach, tofu, fortified cereals)	Absorption can be inhibited by phytates and tannins.
Vitamin B12	High (meat, fish, dairy)	None (naturally)	Requires fortified foods or supplementation.
Complete Protein	High (all animal products)	Present (quinoa, soy, complementary proteins)	Combination of plant sources often needed.
Dietary Fiber	None	High (legumes, grains, vegetables, fruit)	Excellent for digestive health.
Saturated Fat	Often high	Generally low	A health advantage of plant-based diets.

Conclusion

While eating less meat can make you tired, this fatigue is usually preventable and temporary. A shift in nutritional focus is needed to ensure sufficient iron, vitamin B12, and calories. Prioritize diverse plant-based foods, use fortification and supplements, and enhance nutrient absorption to maintain energy. If fatigue persists, see a healthcare professional to check for deficiencies. The Mayo Clinic offers more information on transitioning to meatless meals.

Frequently Asked Questions

People often feel tired after giving up meat because they may be missing out on key nutrients that are abundant in animal products, particularly easily absorbed iron (heme iron) and vitamin B12. Inadequate calorie intake from less energy-dense plant foods can also be a factor.

To get enough iron while reducing red meat, focus on plant-based sources like lentils, beans, dark leafy greens (spinach, kale), fortified cereals, and dried fruits. Always pair these foods with a source of vitamin C (e.g., bell peppers, oranges) to enhance absorption.

Yes, vitamin B12 is a significant concern because it is found almost exclusively in animal products. Those eating less meat, and especially vegans, should regularly consume fortified foods (like plant milks or nutritional yeast) or take a supplement to prevent deficiency.

To ensure adequate calorie intake, increase your portion sizes of plant-based foods and incorporate calorie-dense options like nuts, seeds, avocados, and whole grains into your meals and snacks. Smoothies with ingredients like nut butter and oats are an easy way to boost energy.

For most people, it is not necessary to combine complementary proteins at every single meal. As long as you consume a variety of protein sources (legumes, grains, nuts, seeds) throughout the day, your body can create a complete amino acid profile.

To maximize iron absorption, it's best to avoid drinking coffee or tea with your meals, as the tannins they contain can inhibit absorption. Calcium can also interfere with iron uptake, so consider separating consumption of dairy or calcium supplements from your main meals.

A gradual transition is often recommended. This allows your body to adjust to a new gut microbiome and gives you time to experiment with new recipes and ensure you are meeting your nutritional needs, rather than feeling overwhelmed or fatigued from a sudden change.