Can Anemia Cause Weight Gain? How Low Iron Levels Disrupt Metabolism, Appetite And Energy


Feeling tired and notice you’ve put on some extra pounds recently? Anemia, or low iron levels in the blood, is one potential cause of unexplained weight gain in some people.

Let’s analyze how the fatigue and changes that arise from anemia can contribute to weight gain.

Anemia And Weight Gain: What’s The Connection?

Anemia occurs when the number of red blood cells or hemoglobin concentration drops below normal levels. This reduces oxygen supply throughout the body, resulting in exhaustion, impaired concentration, and sometimes rapid heart rate or shortness of breath. 

Anemia And Weight Gain

However, anemia can also influence metabolism and energy balance in ways that lead to weight gain in some individuals. Understanding these mechanisms allows you to target the root causes contributing to your fatigue and weight changes through proper treatment.

Does Anemia Slow Metabolism? 

Yes, iron deficiency anemia can reduce your resting metabolic rate or number of calories burned at rest:

➜ Low iron inhibits the activity of thyroid hormones that control metabolic rate. 

➜ Anemia suppresses levels of mitochondria that burn calories in cells.

➜ Oxygen and iron shortages prevent optimal energy production from food.

This modest metabolic slowdown contributes to fatigue and lethargy characteristic of anemia. It may also make weight gain somewhat more likely if calorie intake remains high.

Can Anemia Increase Appetite And Calorie Intake?

Anemia often coexists with increased appetite and cravings for non-nutritious foods, especially sweets and starches, which can lead to overeating:

  • Fatigue from anemia reduces motivation to grocery shop and prepare healthy meals. Convenience foods are easier to grab.
  • Sugars and refined carbs provide a quick energy boost to counteract low energy from anemia. 
  • Some studies suggest iron deficiency directly increases the appetite hormone ghrelin while suppressing leptin. This dual effect spurs hunger. 

Combating constant exhaustion may lead some to increase calorie intake unconsciously.

Give in to these unhealthy cravings sparingly and be mindful of portion sizes to avoid significant weight gain.

Does Anemia Reduce Exercise Ability?

The fatigue and muscle weakness caused by anemia can make getting regular exercise more challenging:

– Low endurance and stamina prevents optimal aerobic activity needed for calorie burning.

– Muscle weakness impedes strength training that helps build metabolism-boosting muscle.

– Exhaustion often leads to a more sedentary lifestyle and reduced calorie expenditure.

– Shortness of breath from low oxygen supply inhibits vigorous workouts.

Prioritizing rest and recovery is important with anemia. But light activity that respects your limits can help mitigate fat storage.

Can Anemia Cause Fluid Retention?

Some individuals notice bloating, swelling, or increased puffiness in the face and limbs with anemia:

– Anemia reduces oxygenation needed for lymph drainage and circulation. This allows fluid accumulation in tissues.

– Low protein levels associated with iron deficiency impair normal fluid balance.

– Hormone changes from hypothyroidism triggered by anemia exacerbate fluid retention.

This type of fluid retention typically resolves once iron levels normalize. Diuretics are rarely needed.

Does Treatment For Anemia Lead To Weight Gain? 

Treating anemia through iron supplementation, vitamin C and B12, and dietary changes reverses fatigue and brain fog for most patients. But some notice an initial extra uptick in weight when first starting therapy:

– Increased iron rapidly boosts thyroid hormone levels, which can temporarily overshoot normal metabolism.

– Appetite hormones normalize faster than eating patterns, sometimes spurring overeating initially.

– Rapid metabolism changes from treatment can release toxins that lead to fluid retention at first.

With patience and lifestyle adjustments, this temporary effect levels off and turning anemia around facilitates getting back on track with fitness routines and weight goals.

Tips To Avoid Weight Gain With Anemia Recovery

When recovering from anemia, employ these strategies to prevent packing on excess pounds:

– Gradually increase activity levels in tandem with energy improvements. 

– Limit empty calorie foods; focus on building nutrition back up through whole foods.

– Drink plenty of water and herbal tea to reduce fluid retention.

– Be patient – it takes time for appetite hormones to stabilize. Avoid emotional or boredom eating.

– Set reminders to eat regularly and prevent energy crashes leading to poor food choices.  

– Practice mindful, intuitive eating and relearn hunger cues.

– Follow your physician’s treatment plan to restore iron and vitamin levels steadily.

Medical Causes of Unexplained Weight Gain to Consider

While anemia can contribute to weight gain in some cases, other medical causes to consider include:

– Hypothyroidism 

– Cushing’s syndrome

– Polycystic ovarian syndrome (PCOS)

– Depression or anxiety medications

– Insulin resistance and prediabetes

– Congestive heart failure

Discuss any unexplained weight changes with your doctor to uncover any underlying issues needing treatment. Significant fatigue warrants screening for anemia and nutrient deficiencies.

When To Seek Evaluation For Anemia?

Consult your physician if the following anemia red flags develop:

– Rapid heart rate, chest pain, or shortness of breath with minimal activity

– Dizziness, feeling faint, or confusion

– Severe fatigue impacting normal function 

– Strange food cravings like chewing ice or dirt

– Numbness, tingling, or coldness in hands and feet

– Menstrual periods heavier than usual

– Difficulty concentrating and attributing it to “baby brain” or aging

Diagnostic blood work helps identify the type of anemia and optimal treatment approach.

While correcting anemia can initially cause fluid shifts, you can take proactive steps to get back on track:

– Follow your doctor’s anemia treatment plan as prescribed.

– Increase high-iron foods like red meat, beans, spinach, nuts, and fortified cereals. Include vitamin C for iron absorption.

– Engage in regular light exercise like walking as energy levels allow.

– Set reminders to eat frequent, balanced meals and snacks.

– Reduce refined sugars and carbs that cause blood sugar spikes and crashes.

– Stay hydrated to minimize fluid retention.

– Create meal plans and prep food ahead of time when energy permits. 


In summary, anemia can contribute to weight gain in some individuals due to its effects on metabolism, appetite, fluid balance, and exercise capacity. A multifaceted approach combining anemia treatment, nutrition, physical activity, and patience helps overcome the changes that led to weight fluctuations initially.

Work closely with your doctor to optimize iron levels, vitamin status, thyroid health, and overall well-being. With your anemia properly managed, your body can once again find its healthy set point.


1. How can you stop weight gain caused by anemia?

Treating the underlying anemia through iron supplementation, vitamin C intake, thyroid medications if needed, diet improvements, and gradual increases in activity as energy permits help prevent and reverse weight gain.

2. Does anemia cause belly fat?

Anemia can lead to some fluid accumulation or bloating. But significant abdominal fat or adipose tissue increase requires a positive calorie balance from overeating. Anemia alone does not directly increase belly fat.

3. Can you be overweight and anemic

Yes, it is possible to suffer from obesity and iron deficiency anemia concurrently. Anemia in overweight individuals warrants evaluation for sources of occult bleeding and malabsorption issues. Treatment for both conditions is important.

4. Does taking iron pills make you gain weight

Iron supplementation does not directly cause weight gain. But the energy boost it provides can increase appetite initially if eating patterns are not adjusted. Follow a balanced diet and activity routine to prevent overeating.

5. Can anemia be cured permanently?

For chronic conditions causing anemia like heavy periods or iron malabsorption, lifelong management is often required. But addressing reversible underlying factors and maintaining healthy iron, vitamin B12 and folate levels can prevent recurrence of anemia.

Dr. Jun Ren is a dedicated and experienced registered dietitian and nutritionist who is committed to helping people achieve their health goals through personalized nutrition plans. With a passion for promoting healthy eating habits and preventing chronic diseases, Dr. Ren has been able to assist numerous clients in improving their overall quality of life.

Leave a Comment