Putting on weight requires eating more calories from nutrient-rich foods. Taking vitamins to gain weight is only effective if you have a nutrient deficiency that has caused you to lose weight. Some nutrient deficiencies that could cause weight loss include vitamins C, B12 and folate.
Nutrient Deficiencies and Weight Loss
Most people who eat a balanced diet can get all the vitamins they need from food and avoid deficiencies. But eating an unhealthy diet or having certain conditions that affect the way your body absorbs nutrients can cause your blood levels to drop. When this happens, especially over a long period of time, you will start to notice symptoms.
Deficiencies in vitamin C, vitamin B12 and folate can lead to a condition called anemia, in which the body can't make enough red blood cells. The primary symptoms of anemia are fatigue, shortness of breath, muscle weakness, dizziness, irregular heart beat, personality changes, mental confusion or forgetfulness, loss of appetite and weight loss.
Causes of Anemia
Vitamin C deficiency is typically caused by poor nutrition or problems absorbing the nutrient. Smokers are at an increased risk of low vitamin C because smoking interferes with absorption. Those with chronic illnesses such as kidney disease or cancer also have a higher risk of deficiency.
B12 deficiency is sometimes caused by lack of intrinsic factor, a protein made in the stomach that is required for the body to absorb the vitamin. It can also be caused by surgery that has removed or bypassed part of the small intestine, a restrictive vegetarian diet, having all or part of the stomach removed, medications, aging and autoimmune conditions like Type 1 diabetes.
A deficiency in the B vitamin folate — called folic acid in supplement form — is usually caused by low dietary intake, malabsorption disorders and medications. Pregnant women have increased folate needs and are at a higher risk of becoming deficient, as do people being treated with hemodialysis for kidney failure. Certain drugs used in cancer treatment can affect folate metabolism, resulting in low folate levels.
Vitamins to Gain Weight
If you have lost weight due to a nutrient deficiency, you should not try to correct the problem yourself. Go to your doctor for a diagnosis and treatment plan. Typically, correcting a deficiency involves short- or long-term use of supplements combined with an increased dietary intake of the nutrient. If there is an underlying condition or a medication that is interfering with absorption, your doctor can address that in your treatment plan.
In the meantime, be sure you are getting at least the daily recommended intake (DRI) for vitamins C, B12 and folate determined by the Food and Nutrition Board of the National Academies of Medicine to be appropriate for the general population. These amounts vary depending on whether you are male, female, pregnant or breastfeeding.
- Men — 90 milligrams
- Women — 60 milligrams
- Pregnancy — 85 milligrams
- Lactation — 120 milligrams
- Men — 2.4 micrograms
- Women — 2.4 micrograms
- Pregnancy — 2.6 micrograms
- Lactation — 2.8 micrograms
- Men — 400 micrograms
- Women — 400 micrograms
- Pregnancy — 600 micrograms
- Lactation — 500 micrograms
Maintaining these intakes, or the amounts your doctor recommends, will help normalize your blood levels. As this happens, you should start to gain back the weight you have lost.
Calories to Gain Weight
Whether or not you have had a nutrient deficiency that has caused weight loss, your diet is the most important factor in gaining weight. Consistently not meeting your daily calorie needs can cause you to enter a calorie deficit, in which your body is burning more calories than you are consuming. This causes the breakdown of both fatty acids and lean muscle mass, resulting in weight loss.
If you are not sure how many calories you need to gain weight, it's important to talk to your doctor. Calorie requirements are individual and depend on gender, age activity level and other factors such as genetics, medications and medical conditions.
You can get a rough idea of your calorie needs to maintain your weight using estimates from the Dietary Guidelines for Americans, 2015-2020. For example, moderately active men between the ages of 26 and 45 need 2,600 calories per day, and moderately active women in the same age group need 2,000 calories per day. Being moderately active means you engage in physical activity equivalent to walking 1.5 to 3 miles per day at a pace of 3 to 4 miles per hour. This is in addition to your activities of daily living.
If you are not meeting your daily calorie requirements, simply increasing your intake to meet these goals can help you put on pounds. If you are meeting your calorie needs already, then you will need to increase your intake above the recommended amounts. People with fast metabolisms, who often struggle to gain weight, need to eat more than people with slower metabolisms to achieve the same weight.
A good goal is to start with a modest increase of 250 to 500 calories per day, then increase it as necessary over a period of weeks or months. Gaining weight slowly will help you avoid putting on a lot of fat, especially if you are engaging in an exercise regimen including resistance training.
Focus on Healthy Foods
Gaining weight isn't just about calories. You can eat pizza all day and get a lot of extra calories, but you're also going to get a lot of saturated fat and simple carbs, both of which can wreak havoc on your health. If you are working on fixing a nutrient deficiency, it is especially important to eat foods rich in that nutrient. For example:
If you are low in vitamin C, eat red and green bell peppers, citrus fruits, kiwi, strawberries, Brussels sprouts, cantaloupe and cauliflower.
In general, a healthy weight gain diet should include whole foods, including: carbohydrates from fruits, vegetables and whole grains; protein from fish, chicken, beans and dairy; and healthy fats from avocados, olive oil, nuts and seeds. The latter category should definitely be high on your weight gain foods list because fats are higher in calories than carbs and protein. Adding these to your meals can help you increase the calorie content.
If you are having trouble getting enough calories through solid foods, you can try adding some nutrient-rich smoothies, including ingredients such as full-fat yogurt, nuts and seeds, avocado and coconut oil. You can also try eating several smaller meals per day instead of three large meals.
- Mayo Clinic: "Vitamin Deficiency Anemia"
- Johns Hopkins Medicine: "Vitamin B12 Deficiency Anemia"
- Journal of Dermatology & Dermatologic Surgery: "Scurvy as the Tip of the Iceberg"
- National Academies of Medicine: "Summary Tables, Dietary Reference Intakes"
- Journal of the Academy of Nutrition and Dietetics: "Time to Correctly Predict the Amount of Weight Loss with Dieting"
- NIH: "Factors Affecting Weight & Health"
- Health.gov: "Dietary Guidelines for Americans, 2015-2020: Appendix 2. Estimated Calorie Needs per Day, by Age, Sex, and Physical Activity Level"
- NIH: "Vitamin C"
- NIH: "Vitamin B12"
- NIH: "Folate"
- Mayo Clinic: "What's a Good Way to Gain Weight If You're Underweight?"