Tips to gain weight

If you have a low body weight – which is classed as a body mass index (BMI) below 18.5 — your body may not be getting all the nutrition it needs. So, it’s important to speak to a healthcare professional if you haven't already done so.

While being underweight does not directly cause diabetes, you can be underweight and have any type of diabetes or prediabetes.

To help you gain weight safely, we have some tips to help you, plus information on how your healthcare team, GP or dietitian can support you.

On this page:

Our tips for gaining weight

Our tips will help you pack more nutrition into your meals and snacks, as well as extra calories. You may also find the tips helpful if you don't feel like eating much.

1. Focus on foods you enjoy and be less strict

We all have different food preferences, and these can change over time, so find foods and drinks you enjoy. It may mean eating and drinking things that are higher in fat and calories. For example, if there is something you’d like to try that has a red or orange food label rather than green, this could encourage you

2. Have smaller meals and snacks – but more often

Eating smaller meals and snacks — but more of them — can get your body used to eating more regularly.

It also means you don’t feel too overwhelmed by larger volumes of food at mealtimes. If you're taking certain medication, you may sometimes need to eat at specific times. But where you can, think more about eating what you fancy at a time that suits you - rather than being stuck to a schedule.

3. Have full fat milk, cheese and yogurt

Dairy provides a valuable source of nutrients. If you usually have reduced fat cheese and yoghurt or semi-skimmed milk, it may be worthwhile trying full fat. Although the protein and calcium are similar, you'll get the extra calories. This can be helpful when you have a low appetite or are trying to gain weight.

Research also suggests, yoghurt and cheese, known as fermented dairy products do not increase cardiovascular risk. Cheese is often high in saturated fat but in fermented dairy, this type of fat behaves differently in the body.

4. Enrich meals by adding dairy or dairy alternative ingredients

There are simple ways you can make meals more nourishing, for example:

Grating cheese into soups or pasta dishes (for example, adding 25g cheese will give you approximately 104 kcal and 6g of protein).
Adding a tablespoon of cream to porridge or rice pudding
Adding milk or cream to mashed potatoes or root vegetable mashes
Serving vegetables with spread or grated cheese.
Using full fat cream cheese as a sweet or savoury topping for jacket potatoes, toast, crackers or as a mini cheesecake on top of crushed biscuits
Adding milk powder to your cereal. Use full fat milk powder (sometimes called full cream milk powder). One way is to whisk the powder into whole milk. Follow the instructions on the packaging.
Add a spoonful of nut butter for additional calories and protein to full fat natural or Greek yoghurt served with fruit.

5. Have healthy fats more often (unsaturated)

Eat more foods that have healthy fats:

When cooking or in dressings, use vegetable oils like olive, rapeseed or sunflower.
Have avocado, nuts and seeds for snacks (for example, try half an avocado with an omelette or scrambled eggs on toast. Or have avocado as a sandwich filling with cheese or on top of crackers with full fat cottage cheese).

6. Get advice on nutritional food supplements

Some people may struggle to get enough extra calories and nutrition from food alone. If that applies to you, ask your healthcare team or dietitian about nutritional supplements, and if they are appropriate for you.

These supplements are available in the form of pre-made or powder milkshakes, puddings or juices. Some need a prescription. Others can be bought over the counter. For general advice, speak to your pharmacist.

When to get help if you’re underweight

We all have different body shapes. But if you’re underweight, it’s important speak to a healthcare professional if you haven't already done so.

It's particularly important if:

you have lost weight without meaning to
you have lost a lot of weight quickly
you have lost your appetite because of life challenges or illness
you are unsure what foods to eat to help manage your weight and nutrition.

How can being underweight affect your health?

If you have a low body mass index (BMI) your body may not be getting all the nutrition (such as protein, vitamins and minerals) it needs. This is known as malnutrition. It can also affect people who have had rapid weight loss.

There may be different reasons for being underweight. You may not be eating enough to meet your nutritional needs. Or you could have higher nutritional requirements due to an injury or illness. How this affects blood sugar levels will be different for everyone. This is because it depends on how you treat your diabetes. And if you have another health condition or illness that affects your blood sugar levels, this could make diabetes more difficult to manage.

Not having all the nutrition your body needs can:

make you more likely to pick up infections
reduce muscle strength and energy levels
make it harder to carry out daily tasks and live your life.

How can a healthcare professional help me?

Living with underweight can be caused by underlying physical or emotional problems. So your healthcare professional will chat to you about your health and do any checks needed. They can either rule out problems or offer support and treatment if needed.

For example, if are your body is missing out on certain nutrients and you have a deficiency they may be able to prescribe supplements.

Your healthcare professional can also advice you on gaining (or regaining) weight. They can also offer general tips on what to eat. And refer you to a dietitian.

How can a dietitian help?

A dietitian can chat to you about what foods you might like to eat to help you manage your weight. They’ll make sure you’ll have the nutrition you need from the food you’d like to eat. They can suggest meal plans. They can also recommend nutritional supplements. These are in the form of food and drink, such as shakes, puddings or juices.

Concerns about dietary changes and blood sugar levels

If you’re worried about how different foods and weight gain may affect your blood sugar levels, talk to your healthcare professional or dietitian. This may be a concern if you’re trying to reduce your risk of type 2 diabetes. If you have diabetes, they can advise you on managing blood sugar levels and food intake — and diabetes medication too if you take it.

Can you be underweight and have diabetes?

You can be underweight and have any type of diabetes or prediabetes. Being underweight does not directly cause diabetes.

But being underweight and chronically malnourished, particularly in childhood and adolescence has been linked to a new type of diabetes called type 5. It was recognised by the International Diabetes Federation (IDF) in April 2025.

Type 5 diabetes is estimated to affect between 20 to 25 million people worldwide primarily in Asia and Africa. It is currently thought to be rare in the UK – but we do not have a reliable estimate.

Can diabetes cause you to be underweight?

Weight loss is one of the symptoms of diabetes. Before a diagnosis of diabetes, some people lose a significant amount of weight, quite quickly, and this can lead to a low body mass index. You should be supported by your healthcare team to manage body weight and eat as healthily as possible. This could include advice on how to re-gain weight lost before diagnosis.

What medication can help you gain weight?

Nutritional supplements in the form of food or drink are sometimes prescribed by dietitians to help people meet their nutritional needs and gain weight. Some diabetes medications like sulphonylureas or insulin can encourage weight gain, and this may be considered when deciding the most appropriate medications for individuals.

Get more support

We're here to support you as well as your healthcare team or GP. If you have any questions or just want to talk things through, don't hesitate to call our helpline and speak to one of our trained advisors on 0345 123 2399. You can also get advice and support from people with diabetes through our safe and welcoming online forum.

Content last reviewed

12 October 2026

Next review due

12 October 2029