Weight gain

Nutritional therapy for weight gain can support your healthy weight gain journey and ensure it is sustainable and realistic for a healthful future.

If you are underweight, you may find you come up against health challenges such as fatigue and a weakened immune system. Sometimes illness itself leads to unintentional weight loss; if you are losing weight suddenly without trying, it’s worth visiting your doctor to check there are no medical causes.

If you have the all-clear from your doctor and want to gain weight to support your health and wellness, seeking support from a nutrition professional may help. 

In this video, nutritional therapist Esther Donoff shares some general considerations on how to adapt both your diet and lifestyle to help you gain weight healthily. 

Causes of low weight

There are several factors that may lead to someone being underweight. For some, it’s down to family genetics and a naturally slight figure, for others an illness may be the cause. Below are a few examples of what could cause a low weight:

  • a high metabolism (those with high metabolisms may struggle to gain weight even when eating high-energy foods)
  • genetic disposition (for some, low weight runs in the family)
  • frequent exercise (those who are very physically active may find they have a low body weight)
  • physical illness (illnesses like diarrhoea may cause you to lose weight temporarily while long-term conditions like diabetes, cancer and digestive issues can lead to ongoing weight management struggles)
  • mental illness (some mental health conditions can affect weight, including depression, anxiety and eating disorders)

If you’re concerned about illness, whether it’s regarding your physical or mental health, visit your doctor for support and treatment advice.

Nutritionists dealing with weight gain

Older adults and unintentional weight loss

Sometimes when we get older we may find we lose weight. This can be due to illness or simply a loss of appetite. Being underweight as an older adult can be especially serious, risking health problems like fragile bones and susceptibility to infection.

If a lack of appetite is affecting your weight, try switching up your portion sizes and eating smaller meals more frequently rather than three big meals. Eating with friends and family can help to increase your motivation to eat too.

If you struggle to prepare food try nutritionally balanced ready meals, keeping tinned and dried fruit and frozen vegetables. You may also want to consider having your meals delivered through ‘meals on wheels’.

Risks of being very underweight

In a society that often praises bodies at a low weight, you may think there isn’t a problem with being underweight. The truth, however, is that being very underweight can lead to health problems. Below are a few to be aware of.

Nutritional deficiencies

If you’re underweight, you may not be taking in key nutrients your body needs. If you don’t consume enough iron, for example, you could develop anaemia which makes you feel very low in energy.

Fertility problems

If you menstruate and become very underweight, you could find your period stops. This can lead to difficulties for those trying to conceive.

Weakened immune system

Being underweight can affect the immune system, meaning it won’t work properly. When this happens, the body is less able to fight infections and you may find you pick up viruses and infections more easily.

Skin, hair or teeth problems

If you are deficient in certain nutrients, you may notice your skin, hair and teeth are affected. You may notice dry skin, thinning hair or problems with your dental health.


The food we consume gives us energy. If you’re not eating enough energy-giving foods, you may feel more tired than normal. This can make day-to-day tasks more difficult.


Bone health can be affected if you’re underweight, especially if you aren’t getting enough calcium in your diet. Osteoporosis is a condition that causes bones to be more brittle and prone to breaking. 

How to gain weight

Ensuring your diet is balanced and provides enough calories for your height, age and activity levels is key. As tempting as it may be to start eating as much as you can to gain weight quickly, it’s better for your body if you gain weight slowly.

Avoid relying on a diet full of foods that contain lots of sugar and saturated fat. This type of diet is likely to increase body fat and may affect cholesterol levels and overall health. Instead, look to eat a nutritionally balanced diet that contains regular meals and snacks. Current guidelines from the NHS recommend adults aim to eat:

  • at least five portions of fruit and veg every day
  • meals based on starchy carbohydrates like pasta, rice or potatoes
  • some dairy (or dairy alternative), try full-fat milk while trying to gain weight
  • protein such as fish, meat, eggs, pulses and beans
  • two portions of fish a week (one of which should be oily, like salmon)
  • unsaturated oils and spreads in small amounts

We want to make sure that every mouthful you’re having is really nutrient and energy-dense, so we talk about food being energy-dense as they amount to calories in a particular food.

- Esther Donoff on how to gain weight.

They also advise plenty of fluids (six to eight glasses a day) but recommend avoiding just before eating as this can make you feel too full to eat.

Eating a wide variety of foods will help you get the nutrients you need while keeping your palate interested. Try to bring more joy into your mealtimes and celebrate food with social gatherings now and then.

If you feel you could benefit from professional support, contact a nutritionist.

How a nutritionist can help

A nutritionist will be able to work with you to create a plan for you to gain weight slowly and healthily. If you have any digestive issues (such as an allergy or intolerance) or a special diet (if you’re vegan for example) they will take all of this into consideration.

Before you meet with them, they may ask you to keep a food diary so they can understand your current eating habits. This will help them see where any gaps may be in terms of calories and nutrition. They may also ask you about your general health, mood and well-being (anything that may contribute to a lack of appetite).  

Helping you to set tangible goals is another way nutritionists can support you. Often we have a rough idea of our goals, but making it specific and putting a timescale on it can be tricky. This is what a nutritionist can help with, offering an unbiased and realistic view.

- Read more about how a nutritionist can help you attain weight goals.

The aim of the nutritionist will be to create an eating plan that you will enjoy and stick to in the long term, making adjustments as necessary once you reach a healthy weight. It’s important, therefore, to be honest with them and let them know if there are any parts of their plan you are struggling with. Together you can make changes to ensure you’re enjoying the food in your plan.

Having regular sessions with a nutritionist will help you stay motivated and offer a sense of accountability. They can also offer gentle encouragement and answer any nutrition-related questions you may have along the way. Having this sort of professional support can be invaluable in finding a sustainable way to gain weight.

Related topics

Search for a nutritionist
Would you like to provide feedback on our content?

Find a nutritionist dealing with weight gain

All therapists are verified professionals.

Related Articles

More articles