Do Iron Pills Make You Gain Weight? (+4 Tips for Getting Your Daily Dose!)

Iron deficiency is the most common nutritional deficiency in the world. Symptoms can be generic and masked as other underlying issues, which means iron deficiency can quickly go unrecognized.

For those who have experienced fatigue, lethargy, brittle nails, and sensitivity to cold and can’t seem to figure out why, it may be time to have your iron levels checked. If you are low, iron supplements may be administered to quickly increase levels and get you out of the red zone.

As effective as iron pills are, some people may have concerns about side effects -- including rumors that iron supplementation will make you gain weight.

So is it true? Do iron tablets make you gain weight? This article dives into iron pills and weight gain and explores whether or not taking iron supplements can cause you to pack on extra pounds. Let's get to it!

Key Takeaways

• Iron is essential for health: it is crucial for red blood cells to carry oxygen, for energy metabolism, and for optimizing overall cellular function in the body.
• Iron deficiency anemia may have an indirect association with weight gain because it saps the energy, motivation and metabolic function required for exercise and weight management.
• Most evidence seems to associate poor iron status with overweight, obesity and weight gain.
• A couple of smaller studies are more specific: One links iron supplementation to weight gain; another links it to weight loss.
• Addressing iron deficiency with iron-containing foods and iron pills can help overall health while supporting weight management goals.
• Consult with your doctor! While iron pills are helpful for correcting iron deficiency anaemia, excess iron intake (especially in the non-deficient) may carry potential health risks.

What Is Iron And Why Do We Need It?

Iron is an essential micronutrient and the most abundant metal in the human body.

Why is iron important? It’s involved in the body's ability to perform several critical physiological functions, including:⁽¹⁾

• DNA production
• Enzyme synthesis
• Oxygen transportation
• Immune function
• Red blood cell production

Iron is found in the highest concentrations in animal proteins in the form of hemoglobin and myoglobin. It’s released from these proteins by enzymes in the stomach and small intestine.

Once metabolized, most iron is sent to bone marrow for hemoglobin synthesis, with only a tiny percentage sent to the liver for storage.⁽²⁾

Prolonged low iron intake can deplete iron stores and lead to iron deficiency anemia, which is associated with impaired physical, cognitive, and immune function.⁽³⁾

Iron deficiency is the number one nutritional deficiency in the world. It is also one of the most common nutrient deficiencies in the United States, affecting about 10 million adults.

Even without iron deficiency anemia, low iron status can still lead to unpleasant symptoms, including fatigue, brain fog and weight gain.

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How much iron do adults need to maintain health?

The recommended daily allowance (RDA) of iron to maintain healthy function and avoid deficiency is generally between 8 mg and 18 mg.

The United States National Institutes of Health (NIH) recommendations:

• Adult Men (19 years and older): 8 milligrams (mg) per day.
• Adult Women (19-50 years): 18 mg per day.
• Pregnant Women: 27 mg per day.
• Breastfeeding Women: 9 mg per day.
• Adults 51 years and older: 8 mg per day.

These RDAs are designed to maintain enough iron stores in the body to support healthy functioning of oxygen transport, energy metabolism, thyroid hormone conversion, enzyme activities and more.

Keep in mind, however, that factors like dietary intake, health status, and menstrual cycle for women (especially during heavy periods) can all influence individual needs, as well. It's important to consult with your doctor regarding iron intake.

Research Related to Iron and Bodyweight

There is not that much human clinical research on gaining weight and losing weight, specifically.

Most evidence points to a links between poor iron status and unhealthy weight.

Iron deficiency is often associated with obesity. Scientists have several hypotheses, but the exact reasons why obesity is connected with iron deficiency and anemia remain unclear. Let's take a look at some of the research.

• Researchers in one clinical review suggested that obesity affects every step of iron metabolism, including iron absorption, storage, transport and utilization. They further suggested that obesity makes it harder for the body to absorb and utilize iron, which in turn may contribute significantly to obesity-related metabolic issues.⁽⁴⁾
• A study explored the link between body weight and iron deficiency in children aged 2-16 using data from the National Health and Nutrition Examination Survey III (1988-1994). Researchers reported that higher BMI (body mass index) was associated with a higher prevalence of iron deficiency. Overweight children were about twice as likely to be iron-deficient.⁽⁵⁾
• Researchers studied 50 obese postmenopausal women and 50 non-obese women as a control group. They measured traditional iron levels and soluble transferrin receptor (sTfR) levels, a marker of early iron deficiency. Researchers reported that obese women had higher sTfR levels but similar ferritin levels compared to the control group, suggesting moderate iron deficiency in obese adult women.⁽⁶⁾
• One study investigated the link between serum furin levels and abdominal obesity in 892 Chinese adults over four years. Serum furin levels activates hepcidin, which regulates iron absorption and release. Researchers found that higher baseline serum furin levels were associated with a 19% lower risk of becoming abdominally obese, but also acknowledged that more research is needed.⁽⁷⁾
• A study explored the relationship between iron treatments and weight gain in female patients with iron deficiency anemia who received iron therapy. After three months, 30 of 33 patients showed a significant increase in hemoglobin (Hgb) while 20 gained 3 to 11 kg in bodyweight. Researchers suggested that weight gain is a common issue during iron therapy.⁽⁸⁾
• Finally, a study examined whether iron treatments for iron deficiency anemia cause weight gain. Twenty-one women were assessed before and 4-6 months after starting iron therapy. Results showed significant reductions in waist circumference, body weight, and BMI after taking iron supplements.⁽⁹⁾

Possible Reasons Why Iron May Influence Weight

Energy Levels

Iron is essential for energy metabolism, including the production of ATP (adenosine triphosphate), which is the primary energy currency of cells.

Iron also plays a crucial role in blood oxygenation by binding to hemoglobin, a protein in red blood cells that transports oxygen throughout the body.

As oxygen is carried efficiently to tissues and organs, it enhances cellular metabolism and energy production.

When iron levels are low (especially in cases of anemia), energy production can be compromised, leading to common symptoms like fatigue and reduced physical activity. Over time, decreased physical activity can contribute to weight gain.

Iron supplements support optimal oxygen transport, which in turn promotes higher energy levels, enhanced physical performance and healthy weight management.

For this reason, many of today's top pre-workout supplements will include some iron in their formulas. Athletes may also opt for iron-free pre-workouts and take iron supplements separately.

You can earn more about essential vitamins and minerals for fatigue and tiredness here.

Fat Metabolism

Iron influences how our body burns fat, especially in brown adipose tissue (BAT), which generates heat and boosts energy use (thermogenesis).⁽¹⁰⁾

When there's not enough iron, it can slow down these processes, leading to less energy being burned. Taking iron pills may help restore your body's optimal ability to burn calories, perhaps more so in iron-deficient people.

Iron also plays a role in maintaining a healthy metabolic rate. Iron deficiency may slow down metabolic processes as the body conserves energy, making it easier to gain weight and harder to lose extra pounds.

Hormonal Regulation

Iron - along with iodine, tyrosine, selenium, and zinc - is needed to facilitate the conversion of T4 (thyroxine) to T3 (triiodothyronine), a critical process in thyroid hormone regulation.⁽¹¹⁾

Low intake of any of these nutrients will impair and reduce T3 production, potentially affecting thyroid function and metabolic rate, which in turn may lead to symptoms of hypothyroid like weight gain.

Since iron deficiency interferes so heavily with the normal function of the thyroid, it can lead to a host of other symptoms, such as fatigue, exercise intolerance, and lightheadedness, all of which can disrupt your ability to work out and cause weight gain over time. Iron supplements may help.

While sufficient iron intake can help restore these functions, more research is needed to understand its effects on metabolism and connection to overweight, obesity and related health concerns (metabolic syndrome).

Why does Iron Deficiency Happen?

Iron deficiency can occur due to several reasons, including inadequate intake of iron-rich foods, impaired absorption of iron, increased iron requirements, or chronic blood loss.

Here are some common causes:

Poor Absorption of Iron: Certain conditions or factors can impair the absorption of iron from food, potentially leading to iron deficiency anaemia. These include gastrointestinal problems and medications that may interfere with iron absorption.

Increased Iron Requirements: There are periods in life when the body's demand for iron increases, such as during pregnancy and breastfeeding. If dietary intake from foods or iron pills doesn't meet these increased needs, iron deficiency can develop.

Intense training: Intense physical activity can increase the body's demand for iron due to higher red blood cell turnover and increased oxygen utilization in muscles. Athletes, especially endurance athletes (runners, cyclists, and triathletes), are at greater risk of developing iron deficiency.

Blood Loss: Chronic blood loss can deplete the body's iron stores faster than they can be replenished, potentially resulting in iron deficiency anaemia. This can occur due to heavy menstrual bleeding, gastrointestinal bleeding (from ulcers or other conditions), or frequent blood donation.

Inadequate Iron-Containing Food Intake: The obvious cause! Not consuming enough iron-rich foods, especially in diets that are low in meat and iron-fortified foods, can lead to iron deficiency. So, if you’re a vegan or vegetarian, iron requirements go up -- especially for premenopausal women on a plant-based diet.

Did you know? The recommended daily intake (RDI) for those following a plant-based diet is 1.8 times higher than for people who consume meat because of the differences in absorption between heme and non-heme iron.⁽¹²⁾ More on that in a moment. Vegans may consider iron supplements.

The most common tests to assess blood iron levels include:

1. Serum Ferritin Levels: Measures the amount of stored iron in the body.
2. Serum Iron: Measures the level of iron in the blood.
3. Total Iron-Binding Capacity (TIBC): Assesses how well the blood binds and carries oxygen.
4. Transferrin Saturation: Calculated from serum iron and TIBC, indicates the percentage of transferrin (a protein that transports iron) that is saturated with iron.

These tests are often used together to give a comprehensive picture of overall iron status.

Addressing iron deficiency typically involves increasing iron intake through diet or taking an iron supplement, identifying and addressing the underlying cause, and managing issues that affect iron absorption or utilization -- all under the supervision of a doctor.

Heme vs. Non-Heme Iron

Dietary iron comes in two forms: heme and non-heme. When it comes to dietary iron absorption, heme is the one to look for.

• Heme iron is more bioavailable and absorbed more efficiently from the gut because of specific heme transporters that enable it to pass directly across cell membranes and enter the bloodstream.
• Non-heme iron cannot use these transporters and requires the reduction of ferric iron to ferrous iron before it can be absorbed.

Animal products like red meat and poultry are the major dietary contributors or heme iron and comprise roughly 55-70% of the iron content of these foods. The remainder of iron, and all iron found in plant foods, is in the form of non-heme iron.

Because heme iron is more well absorbed than non-heme iron, the type of dietary iron consumed may be more indicative of total iron levels than total iron intake.

You also have to consider that iron uptake from plant foods is influenced by other compounds in these foods - they’re what we call anti-nutrients. These substances bind to iron and other minerals, inhibiting their absorption.⁽¹³⁾

These anti-nutrients include things like tannins (red wine, tea), oxalic acid (cocoa, spinach, beetroot, rhubarb), phytate (cereal grains), and phosphate (processed cheese, spreads). Wheat bran, dairy products, soy, and coffee also contain substances that interfere with iron absorption.

But luckily, anyone following a plant-based diet can enhance non-heme iron uptake by adding vitamin C (ascorbic acid) to their meals (we’ll talk more about this below).

4 Tips For Getting Enough Iron

1. Load up on iron-rich foods

For anyone that doesn’t consume red meat, iron has to come from plant-based foods. It can be harder to meet the RDI for vegans, but there is no shortage of plant-based sources.

Whether from tofu or tempeh, nuts and seeds, blackstrap molasses, or yeast extract spreads (marmite, vegemite), loading up your plate with iron-rich foods is the easiest way to ensure you’re consuming enough.

Can’t think of fun and delicious ways to incorporate iron-rich foods? Do a quick Internet search for “iron-rich plant-based recipes” and choose from a wide selection of mouthwatering meals.

2. Get enough vitamin C

As we mentioned, non-heme iron is significantly less bioavailable than heme iron, so you must consume more to ensure your levels stay elevated.

But for those who weren’t aware, consuming non-heme iron alongside ascorbic acid (vitamin C) has been shown to boost iron absorption by a whopping 67% with just 100 mg of vitamin C.

But remember, the enhancement of non-heme iron absorption is directly proportional to how much ascorbic acid is in the meal.⁽¹⁴⁾Learn more about Vitamin C for iron absorption.

3. Get beefy with the beans

Getting heme-iron through red meat isn’t an option if you’re not a meat eater. But although plant foods don’t supply heme iron, beans are a rich source of non-heme iron and make a great substitute in dishes that typically call for beef. Some bean options for dietary iron:

• Lentils
• Black-eyed peas
• Split peas
• Chickpeas
• Soybeans
• Black beans
• White beans
• Kidney beans
• Pinto beans

Plus, they’re rich in all sorts of vitamins and minerals, protein, and fiber.

4. Fill in the gaps with a good supplement

Although diet is the ideal source of iron, we don’t always eat ideally. Some days, we forego the veggies for carbs; other days, we don’t feel like eating protein - it happens. That's where dietary supplements come in. There are a lot of iron products across many different categories in the dietary supplement market. We're about to cover top formulas out there.

Best Iron Supplements

It's important to take high-quality iron formulas. Iron absorbs best on an empty stomach, so clean and premium products are a must to avoid any digestive distress.

All the following options are top-shelf, clean-label iron supplements. Each one features easy-to-absorb NutriGenesis®, a type of iron grown in cultures using a patented eco-friendly process.

Performance Lab® Iron Complex

Enhanced iron formula for supercharged everyday mind & body performance.

Ingredients: Vitamin C (NutriGenesis®) 60 mg, Iron (NutriGenesis®) 14 mg

If you're looking for daily iron mineral support in clean, convenient capsule form, this is the product for you. It supplies 14 mg of high-absorption NutriGenesis® Iron per serving, stacked with NutriGenesis® vitamin C for maximum absorption. Take it to support energy, immunity, cognitive performance and more.

Shop Performance Lab® Iron

Performance Lab® NutriGenesis® Multi

NutriGenesis® nature-identical vitamin and mineral essentials for healthy biological performance.

Ingredients: 24 cultured essential vitamins and minerals complexed with cofactors for optimal potency.

Performance Lab®'s ultramodern multivitamin in customized formulas for men's and women's distinct nutritional needs. Featuring advanced form NutriGenesis® lab-grown vitamins and minerals with cofactors, enzymes and probiotics that enhance their bioavailability, metabolism and utilization. The women's formula has 8 mg iron per serving, while the men's formula supplies 4 mg per serving.

Shop Performance Lab® NutriGenesis®

Pre Lab Pro®

“World’s smartest pre-workout drink": smooth energy, focus and peak performance with no jitters or crashes.

Ingredients: Red Beetroot Powder; Setria® Performance Blend; Natural Caffeine; L-Theanine; L-Tyrosine; Vitamin D3, Potassium and Iron (all as NutriGenesis®), Himalayan Pink Salt. Delicious natural berry flavor.

Iron is important for athletes, so of course the “World’s smartest pre-workout drink" -- Pre Lab Pro® -- includes iron in its formula. This nootropics-enhanced pre-workout formula supplies a moderate dose of sport-tuned caffeine with amino acids and brain-boosters that balance energy with calm control. Take it for better gym performance, muscle growth and muscle gains overall. Each serving (1 scoop) supplies 2.5 mg of iron.

Shop Pre Lab Pro®

Conclusion

So can iron tablets make you gain weight? Or on the contrary, will taking iron pills help you lose weight?

While the relationship between iron levels and extra pounds of weight gained (or lost) is not yet fully understood. But it seems that iron itself, whether from dietary sources or iron tablets, does not directly make affect weight. Instead, the impact of iron status on body weight is largely indirect.

Iron deficiency anemia, characterized by low iron levels in the body, can lead to symptoms such as fatigue, decreased motivation for physical activity, and appetite dysregulation—all of which may contribute to changes in weight over time.

Addressing iron deficiency with some type of iron therapy (being careful not to take too much iron) is essential not only for restoring energy levels and improving overall health but also for supporting healthy weight management.

Following a healthy diet rich with iron, taking a high-quality iron supplement, and consulting with your trusted healthcare professional can all go a long way in in ensuring optimal iron status and the overall well-being it supports.

Related Post: Do Iron Pills Cause Constipation?