Managing your weight with gestational diabetes

Staying a healthy weight by eating well and keeping active will help you manage gestational diabetes.

Staying a healthy weight by eating well and keeping active is one of the best things you can do to manage your gestational diabetes.

Why your weight is important

Anyone can develop gestational diabetes during pregnancy. But your risk of gestational diabetes is higher if you are overweight.

If you are obese (very overweight), you will have extra care in pregnancy

This is because you are at greater risk of some problems, such as high blood pressure

Find out more about being overweight and pregnant.

How will I know if I’m overweight?

The usual way to work out if you are overweight uses the body mass index (BMI). BMI is a measure that shows if you are a healthy weight for your height. 

Your midwife will weigh and measure you at your first antenatal (‘booking’) appointment, to work out your BMI. If you already know your weight and height, you can find out your BMI online.

For most UK adults, a BMI of 25 to 29.9 means you are likely to be overweight, while a BMI of 30 or above is classed as obese. These numbers are a bit different for some ethnicities. Find out more about that here.

How to manage your weight

The best way to manage your weight is to eat a healthy diet and stay active. This will also help you control your blood sugar levels.

Managing your weight with gestational diabetes is not about dieting or trying to lose weight. In fact, your healthcare team will advise you not to try to lose weight by dieting while pregnant. 

Your aim is to look after yourself and your unborn baby by eating healthy meals and staying active. You can then try to lose weight safely after the birth.

Healthy diet and gestational diabetes

Eating a balanced diet that’s low in sugar will help to manage gestational diabetes, and reduce the risk of complications. Aim to eat plenty of fruit and vegetables, and choose foods with a low glycaemic index as much as you can.

Read more about using diet to manage gestational diabetes.

"I felt more in control being able to follow the diet. I was a bit stubborn about it, but it did help."


Exercise and gestational diabetes

Gentle exercise can help to reduce your blood sugar levels and manage your gestational diabetes. It can also help you have a healthy pregnancy in general, and to cope better with labour and birth.

Walking, pregnancy yoga, swimming or aquanatal classes are all great ways to stay healthy and maintain a healthy pregnancy weight. If you have any questions or concerns about what type of exercise is best for you at each stage of pregnancy, talk to your midwife or doctor.

Read more about exercise if you have gestational diabetes.

Gaining pregnancy weight

You will gain some weight during your pregnancy. Because every person’s body differs, there are no official UK guidelines for how much weight you should gain in pregnancy

The main thing is to keep your weight gain at a safe and healthy level for you and your baby. Your healthcare team will monitor you both throughout your pregnancy. 

Even if you are obese (BMI of 30 or above), do not try a weight-loss diet while you’re pregnant. Just focus on eating well and staying active. This should help to avoid too much weight gain in pregnancy, and you may even lose a little bit of weight just by making these simple and safe changes. It should also help you to lose more weight, in a healthy way, after you’ve given birth.

Don’t eat for 2

Friends and family may tell you to ‘eat for 2’ during your pregnancy. This can be very tempting, but you do not need any extra food during the first 6 months of pregnancy. After that, you only need an extra 200 calories a day, which is about half a sandwich.

Read general information about weight management in pregnancy.

What does all this mean for you?

For some people, changing their diet is the hardest thing about having gestational diabetes. Eating foods you love during pregnancy can be a great comfort, and some people also eat to cope with morning sickness

It can feel unsettling to have to make such a big change. But eating well and exercising will improve you and your baby’s health, both now and in the long term. It’s going to be worth it!

Changing your diet may also affect those around you. If you live with anyone, talk to them about making some changes together. For example, you could agree not to keep any junk food at home. 

You may find some of our healthy eating tips helpful. 

"My husband had to change his diet as well as me. We didn’t keep any cakes or sweets in the house!" 


More support and information

You can contact the Diabetes UK Helpline in England, Wales or Northern Ireland on 0345 123 2399 or at [email protected]. If you're in Scotland call 0141 212 8710 or email [email protected].

The Tommy's Midwives' Helpline is a free phone line open 9am to 5pm, Monday to Friday for anyone who needs advice, reassurance or support on any pregnancy or planning for pregnancy issue. You can call 0800 0147 800 or email [email protected]

NICE (2020). Diabetes in pregnancy: management from preconception to the postnatal period. NICE guideline 3. Available at: (Accessed 27 March 2024) (Page last reviewed 16/12/2020) 

NICE (2017). Weight management before, during and after pregnancy. NICE public health guideline 27. Available at: (Accessed 27 March 2024) (Page last reviewed 03/2017) 

Royal College of Obstetricians & Gynaecologists, Diabetes UK (2021). Gestational diabetes - Information for you. Available at: (Accessed 27 March 2024) (Page last reviewed 09/2021)

NHS (2022). Gestational diabetes. Available at: (Accessed 27 March 2024) (Page last reviewed 08/12/2022. Next review due 08/12/2025) 

Review dates
Reviewed: 27 March 2024
Next review: 27 March 2027