I need to put on weight. I am in my thirties, am 5ft 3in and weigh 7st 3lb. I have a very fast metabolism and my blood-sugar level drops quickly. I have no real medical problems, just that I get tired a lot, feel the cold more than most and really want to put on a little more weight. Can you recommend a few meals/snacks that might help me to do this? Some people tell me just to eat protein, others junk food and carbohydrates, but I don't think that can be good. I am also starting to exercise to increase muscle tone - not heavy, but 20 minutes each day.

You say that you have no “real” medical problems. My first piece of advice is: see your GP and check that you have no underlying medical reasons for your lowish weight and other symptoms. If not, and he or she is happy that you just need to change your diet and lifestyle, the advice below could be helpful.

You are right, following odd diets packed with extra protein or full of fat and sugar-laden takeaways, cakes and biscuits is not the way forward. You may want to gain weight, but you do not want to see your cholesterol levels increase, your salt intake go up to a point where it triggers high blood pressure, and you don't want to eat excess sugar as that strains your pancreas.

The aim is for you mostly to lay down extra lean tissue (muscle) rather than lots of extra body fat. This does not mean ending up looking like Sylvester Stallone's Rambo. Unless you take illegal steroids, this is hard for a woman to do.

To gain some extra muscle you need to combine a healthy, balanced diet that contains about 500 calories a day more than you are currently eating with a regular programme of “strength training” exercises. These involve things such as lunges and sit-ups and lifting light weights to work your arm muscles as well. You do not have to go to a gym to do this. There is a website called www.strongwomen.com that shows you routines that you can do in your home. The result of this combination of eating more than normal and regular strength training is that you can expect to gain 1lb-2lb per month.

As far as your food is concerned, start by grasping the concept that ideally you will eat three meals a day and two snacks. It is important to eat regularly so that your muscles get the fuel they need to grow while replacing energy used in exercising.

You can eat normal things such as porridge or muesli, boiled eggs with bread and butter or poached eggs on toast with grilled tomatoes for breakfast. Have a pitta bread, tortilla wraps or wholegrain bread sandwiches for lunch, filled with anything from tuna and sweetcorn to chicken and salad, and for dinner have something such as spaghetti bolognese, a roast meal or a stir-fry with noodles.

Try to have slightly larger servings than you would normally at each meal and add two 100-calorie snacks between meals, such as a large banana, a Müllerlight yoghurt, two oranges, a skimmed milk latte or cappuccino, a toasted crumpet or half a teacake with a little jam, two oatcakes, a slice of malt loaf or 200ml of fruit juice.

Remember that you will gain healthy weight by following this kind of regimen in the long run. It is a fairly lengthy process that takes as much dedication as losing weight does for the rest of us.

Send your nutrition questions to amanda.ursell@thetimes.co.uk

A healthy build-up

If you are a slim-built “ectomorph”, you will find it harder to put on muscle than a more muscular “mesomorph”, but it can be done.

If men want to gain muscle, they need to eat an extra 700 calories a day and do regular strength training. Men can expect to gain 3lb-4lb a month. This gain is because of their higher levels of the hormone testosterone.

Other 100-calorie boosters include an 80g pot of fruit fromage frais, two peaches, apples or oranges, six dried (not ready to eat) apricots, one large slice of wholemeal bread, 2tbsp of sugar-free muesli and 100ml of bean-style soup.

You can add 100 calories to your meal with an extra 30g of pasta (uncooked) or two extra tablespoons of rice (cooked).

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