I’m convinced that antidepressants can have an impact on appetite — some can increase it, and while this is a good thing if depression has led to someone not being bothered to eat, it’s not so great if it makes them eat too much and gain too much weight (which in most instances can make them feel low about their body and lead to other physical problems such as an increase in blood pressure).

Alternatively, as you’re finding with your husband, the appetite can wane, which can mean people don’t eat enough of the foods that are going to make them feel better. Second, certain foods can, independent of medication, have a positive impact on mood by stimulating endorphin production — most notably foods rich in protein and vitamin C.

Many psychiatrists dismiss the notion that eating habits can influence mood, and some GPs refuse to refer to my clinic patients who want to discover how to help themselves feel better without antidepressants. What the sceptics fail to grasp is that many people prefer to treat themselves with simple, but effective, strategies and that any good nutritional therapist will suggest constructive ways in which they can change their eating habits for the better.

Someone who is depressed will often become locked into a destructive eating cycle, yet as soon as their body receives a good balance of mood-boosting foods and is spared the mood-devastating effects of drinking too much alcohol and eating too many destabilising sweet foods, they will feel much better.

The occasional chocolate bar is fine, but if biscuits, chocolates, sweet pastries, ice creams and stodgy puddings are the norm, you’re far more likely to find moods swinging all over the place. This is because the body absorbs sweet foods fast, and as your blood sugar and endorphin levels rise as a result, you initially feel great. The downside is that the surge in blood-sugar levels prompts the production of insulin, the hormone that lowers it, and as your blood-sugar “ crashes” in response, so does your mood.

Endocrinologists dismiss the notion of hypoglycaemia, low-blood sugar, in non-diabetics, but so many people I see feel strong physiological symptoms when their blood-sugar level drops more quickly than they’re comfortable with — they feel hypoglycaemic. The obvious solution may appear to be to eat more chocolate, but the more you eat, the more blood-sugar crashes you experience and the wilder your mood swings become.

The best way to break this circle and to banish sugar cravings is to avoid such foods altogether and instead eat plenty of fresh fruit — which at this time of year is no hardship. Fruit contains sugar, so it will satisfy a sweet tooth, but the body absorbs it so slowly that the gradual rise in your blood-sugar levels encourages a more consistent production of endorphins, meaning that the more fruit you eat, the longer you’ll feel happier.

Patients who change their eating habits and stay away from the quickly absorbed high-glycaemic-index foods can feel their mood is far more consistent, so it’s worth a try.

If you find you’re sensitive to sugar-related mood swings, try incorporating plenty of low-glycaemic foods in your diet — apples, peaches, grapefruits, plums, cherries, dried apricots, pulses, lentils and most green leafy vegetables. As a bonus, many green leaves and fruits, especially satsumas, clementines, grapefruits, oranges and kiwis, are rich in ascorbic acid (vitamin C), the nutrient that stimulates the brain to manufacture endorphins.

The primary endorphin-producers are foods rich in animal protein, such as turkey, chicken, lean red meat, eggs and cheese. These contain two amino acids, tryptophan and L-phenylalanine, that encourage the brain to produce serotonin and noradrenaline. A steak and salad, or a simple dish such as eggs on toast or cold charcuterie, can increase the brain’s supply of amino acids and will make your husband feel happier.

I’d also try to boost the level of omega-3 fatty acids in his diet, as they seem to help to balance brain chemistry and protect against depression. Aim for up to four portions a week (a portion being 140g), though women should just have two portions. Oily fish include salmon (ideally wild), fresh tuna, trout, sardines, herrings and mackerel; vegetarian alternatives include walnuts, walnut oil and hemp or flaxseed oil. Alternatively, try an omega oil supplement such as morEPA, from www.healthyandessential.co.uk.

Make sure that your husband is drinking enough water, as depression and feeling low can be exacerbated by dehydration. He should drink 2.5 litres of water a day — this can include a couple of cups of tea or coffee. Ensure that alcohol intake is minimal, as it can aggravate mood swings and muck around with sleep, which can impact on mood and energy levels. Times Online