What Will Happen to My Body if I Go Vegan?

October 23, 2025 •

4 min read

According to a 2014 meta-analysis, individuals following a vegetarian or vegan diet tend to have a lower body mass index (BMI) than meat-eaters, which often translates to improved heart health. So, what will happen to my body if I go vegan? The transition can bring a mix of effects, from improved digestion and skin clarity to potential nutrient challenges that require careful planning.

Quick Summary

Going vegan impacts the body from day one, affecting digestion, energy, and nutrient absorption. While many experience positive changes like weight loss and clearer skin, it is crucial to manage potential deficiencies in key nutrients like B12, iron, and calcium through a balanced diet or supplements.

Key Points

Initial Adjustments: Expect potential bloating or gas as your gut adapts to increased fiber, but also a possible boost in energy levels and clearer skin in the first few weeks.
Crucial Supplements: A lifelong vegan diet requires supplementation for Vitamin B12, as it is not reliably found in plant foods and is essential for nerve and blood cell health.
Long-Term Health Benefits: A well-planned vegan diet can lower the risk of chronic diseases like heart disease and type 2 diabetes by improving cholesterol, blood pressure, and managing weight.
Micronutrient Management: Pay close attention to intake of calcium, vitamin D, iron, and omega-3 fatty acids, which can be lower on an unfortified plant-based diet.
Healthy Gut Microbiome: The high fiber content fosters a more diverse and healthier gut environment, which supports digestion and overall well-being over time.
Avoid Processed Foods: Focusing on whole plant foods rather than highly processed vegan alternatives is essential to avoid potential health downsides and maximize nutritional gains.

Initial Changes: The First Weeks

The first few weeks after making the switch to a vegan diet can be a period of significant adjustment for your body. Many people experience a noticeable boost in energy levels, attributed to the increased intake of vitamins, minerals, and complex carbohydrates from whole plant foods. As the digestive system shifts away from processing animal products, which can be more difficult to break down, feelings of sluggishness can decrease.

However, this initial phase also comes with potential digestive discomfort. The sudden, substantial increase in dietary fiber can cause temporary bloating, gas, and changes in bowel function. This is your gut microbiome adjusting to its new fuel source. To mitigate these effects, it is recommended to increase fiber intake gradually, drink plenty of water, and ensure good hydration.

Skin and Sensation Changes

For many, one of the most visible changes is improved skin clarity. The removal of dairy, a common acne trigger due to animal hormones, combined with the higher intake of antioxidant-rich fruits and vegetables, can lead to a brighter, softer complexion. Some people also report a change in body odor and a heightened sense of taste as their palate recalibrates to natural flavors.

Short-Term Nutritional Considerations

Even in the short term, new vegans must be mindful of key nutrients. While a healthy vegan diet can be rich in many vitamins, a sudden elimination of animal products without proper replacement can lead to deficiencies. Ensuring a balanced intake of plant-based proteins, iron sources like lentils and leafy greens, and calcium-rich foods like fortified milks is vital from the start.

Long-Term Benefits and Considerations

As the body becomes fully adapted to a vegan diet, the benefits can extend over the long term, impacting various health markers.

Improved Heart Health: Studies have shown that a well-planned vegan diet can significantly lower cholesterol and blood pressure, reducing the risk of heart disease due to its high fiber and low saturated fat content.
Weight Management: Vegans tend to have a lower average BMI and can experience sustainable weight loss. This is because plant-based diets are often lower in calorie density and higher in filling fiber, helping to promote a feeling of fullness.
Better Gut Microbiome: The high prebiotic fiber found in plant foods nourishes beneficial gut bacteria, leading to improved digestive health and a more diverse microbiome. A healthier gut is linked to enhanced overall immunity and mental well-being.

Nutrient Deficiencies Over Time

While the long-term benefits are numerous, certain nutritional considerations become more critical over time. A balanced, whole-foods vegan diet is not enough to prevent all potential deficiencies.

Vitamin B12: This vitamin is crucial for nerve function and blood cell formation and is found almost exclusively in animal products. Over time, stores in the body can become depleted. Long-term vegans must supplement with B12, either through fortified foods or a standalone supplement, to avoid serious health consequences.
Calcium and Vitamin D: Adequate calcium intake is essential for bone health. While plant-based sources exist (fortified milks, tofu, kale), absorption can sometimes be an issue. Combining calcium with sufficient Vitamin D (from sunlight, fortified foods, or supplements) is key for bone strength.
Omega-3 Fatty Acids: The essential omega-3s, EPA and DHA, are less abundant in plant foods. Vegans should incorporate sources like flaxseeds, walnuts, and algae-based supplements to support brain and heart health.

Comparison: Vegan vs. Omnivore Body Impact


Feature	Vegan Diet (Well-Planned)	Omnivore Diet (Typical Western)
Cholesterol Levels	Lower, often significantly reduced.	Higher, particularly LDL ('bad') cholesterol.
Dietary Fiber Intake	Very high, leading to improved digestion.	Often low, contributing to constipation.
Weight & BMI	Tends to be lower.	Often higher, associated with obesity risk.
Saturated Fat	Very low to non-existent.	High, particularly from red meat and dairy.
Antioxidants	Very high, protecting cells from damage.	Variable, depends on fruit/veg consumption.
Vitamin B12 Source	Supplements or fortified foods required.	Naturally obtained from animal products.
Gut Microbiome	Greater diversity of beneficial bacteria.	Less diverse, linked to poorer health markers.
Risk of Chronic Disease	Reduced risk of heart disease, type 2 diabetes.	Elevated risk factors due to diet composition.

How to Transition Successfully

To ensure a smooth transition and maximize health benefits, a phased approach is often best. Instead of switching overnight, try incorporating more plant-based meals into your routine over a few weeks. Start with 'Meatless Mondays,' then progress to more frequent vegan meals. Focus on whole, unprocessed plant foods to avoid the pitfalls of relying heavily on vegan junk food, which can be high in sugar and fat. Seek out resources like cookbooks, online communities, and dietitian advice to plan balanced, delicious meals. For a deeper understanding of nutrient requirements, the Physicians Committee for Responsible Medicine offers evidence-based resources on plant-based nutrition [https://www.pcrm.org/good-nutrition].

Conclusion

For many, going vegan can be a profoundly positive decision, leading to improved heart health, better digestive function, clearer skin, and sustainable weight management. However, it is not a 'magic bullet' and requires deliberate and thoughtful planning. Understanding the potential nutrient gaps, particularly regarding Vitamin B12, Vitamin D, and iron, and proactively addressing them with fortified foods or supplements is key to long-term success. By approaching the transition with awareness and a focus on whole foods, you can ensure your body reaps the rewards of this lifestyle choice while remaining healthy and energized for years to come.

Frequently Asked Questions

Yes, it is highly recommended to take a Vitamin B12 supplement. This nutrient is vital for nerve function and blood health and is not reliably found in plant foods, so supplementation is necessary for long-term health.

Many people do experience weight loss on a vegan diet, as plant-based foods are often higher in fiber and lower in calorie density than typical omnivorous meals. However, weight loss is not guaranteed and depends on overall calorie intake and food choices.

Yes, an initial increase in gas and bloating is very common. This is caused by the sudden increase in dietary fiber as your gut bacteria adjust. It typically subsides as your body adapts over a few weeks.

Vegans get protein from a wide variety of plant-based sources, including legumes (lentils, beans, chickpeas), tofu, tempeh, nuts, seeds, and whole grains. Combining different plant foods throughout the day provides all essential amino acids.

To get enough iron, include iron-rich plant foods like lentils, spinach, kale, and fortified cereals in your diet. To boost absorption, pair these with a source of Vitamin C, such as bell peppers, citrus fruits, or broccoli.

Bone health on a vegan diet requires attention to calcium and Vitamin D intake. Ensuring adequate consumption of fortified plant milks, tofu, and leafy greens, along with Vitamin D supplements, is key to maintaining strong bones.

Yes, but you need to be intentional. Good plant-based sources include flaxseeds, chia seeds, walnuts, and hemp seeds. Algae-based supplements can provide the EPA and DHA forms of Omega-3 that are less efficiently converted from plant sources.