Eating well when your appetite is low

A small appetite makes losing weight easier and eating well harder. When you only want a few mouthfuls, every mouthful has to count. This page is about getting enough protein, vitamins, minerals, fibre and fluid into a body that is not asking for them, and spotting when you have slipped into under-eating.

Small, frequent, protein-dense

When appetite is low, the usual pattern of three meals falls apart: you skip breakfast because you are not hungry, pick at lunch, and by evening you have eaten almost nothing and feel awful. The advisory's practical advice is to eat a small breakfast regardless of hunger, then a small meal or snack every three to four hours, with plenty of fluid between them.^[1]

Make each of those small meals protein-first. Two eggs. A pot of Greek yoghurt. Half a tin of tuna on a cracker. A handful of cooked chicken. Cottage cheese. A glass of milk. Each is 10 to 20 g of protein in a few mouthfuls. Five or six of those across the day gets you close to the target without ever facing a full plate. Leave the low-protein fillers, such as crisps, toast on its own and salad without a protein source, for when the essentials are in.

Liquid protein

Drinking is often possible when eating is not. Options, roughly from simplest to most effort:

• Milk. A 250 ml glass of semi-skimmed milk gives about 9 g of protein plus calcium and B12. Fortified soya milk is the closest plant alternative.
• Smoothies. Milk or yoghurt as the base, a handful of frozen fruit, a spoon of peanut butter or oats. Blend; sip over an hour if you need to.
• Protein shakes. A scoop of whey, pea or soya protein in milk gives 25 to 35 g. Unflavoured powder in a smoothie is less sickly than a sweet ready-made shake if nausea is a problem.
• Soups with protein. Lentil, chicken or bean soups; stir in Greek yoghurt or grated cheese.

Sip rather than gulp, and keep drinks separate from solid meals if you fill up quickly. Managing GI symptoms with food has more on that.

The warning signs of under-eating

Losing weight fast is the aim. Losing it so fast that your body is running short of what it needs is not, and the line between the two is easy to cross when you never feel hungry. Take these seriously:

• Dizziness or light-headedness, especially on standing. Often dehydration, sometimes low blood sugar or low blood pressure.^[3]
• Hair shedding. Hair loss a few months into rapid weight loss is common and usually temporary; the NHS lists weight loss and iron deficiency among the causes.^[4]
• Feeling cold all the time. A body short of fuel turns down the heating.
• Poor sleep, waking hungry at 3 am, or waking unrefreshed.
• Losing strength. If your lifts are going backwards or stairs feel harder, you are losing muscle, not just fat. See preserving muscle.
• Low mood, irritability, poor concentration, constant tiredness.
• Missed periods in women who are not menopausal.

One of these on its own may mean nothing. Two or three together mean eat more, particularly protein, and if it does not improve within a couple of weeks, see your GP. If you are losing more than about a kilogram a week for many weeks, ask to be referred to a dietitian.

Micronutrients: what drops when eating drops

Cutting food by half cuts vitamins and minerals by half, and the ones that come mostly from meat, fish, dairy and fortified foods go first. The advisory recommends screening people losing weight quickly for gaps and considering supplements for at-risk nutrients such as vitamin D, calcium and B12, or a multivitamin-and-mineral tablet.^[1] The NHS reference figures for adults are:

If you are eating a mostly plant-based diet, are a woman with heavy periods, or have been eating very little for more than a few weeks, ask your GP for a blood test rather than guessing. A basic supermarket multivitamin-and-mineral is a reasonable safety net while you wait; it is not a substitute for food.

Fibre, constipation and fluids

Constipation is common with any big drop in food intake, because less food means less bulk and often less fibre and fluid.^[1] The NHS recommends about 30 g of fibre a day for adults, from wholegrains, fruit, vegetables, beans, lentils, nuts and seeds.^[2] Two cautions: build up over a couple of weeks rather than all at once, because a sudden jump causes bloating and wind; and drink more as you add fibre, because fibre without fluid makes constipation worse.^[9]

For fluids, the NHS Eat well guidance is six to eight glasses a day, more in hot weather or when you are active.^[10] Water, milk, tea and coffee all count. Dehydration is a particular risk when you are eating less, because a good share of everyday fluid normally comes from food. Signs are dark yellow, strong-smelling urine, thirst, dizziness, tiredness and a dry mouth.^[3] If you have had vomiting or diarrhoea, oral rehydration sachets from a pharmacy replace the salts as well as the water; plain water alone may not be enough.^[3]

Alcohol

Alcohol is calories without nutrition, it worsens nausea and reflux, and it hits harder on an empty stomach. The advisory recommends keeping intake minimal during weight loss.^[1] The NHS low-risk guideline for everyone is no more than 14 units a week, spread over three or more days, with several drink-free days.^[11] During rapid weight loss, less than that is sensible.

When to see a GP or dietitian

See your GP if:

• you have two or more of the warning signs above for more than a couple of weeks;
• you are struggling to keep down fluids, or have signs of dehydration that do not improve;^[3]
• you have lost a large amount of weight without trying, or faster than you intended;
• you have a condition that affects what you can eat, such as kidney disease, diabetes treated with insulin, or a history of an eating disorder.

Ask specifically for a referral to a dietitian. NHS dietitians are the people trained for exactly this, and specialist weight-management services usually include one; the NHS and licensed options page explains the route. If you have been using an unlicensed product and are unwell, talking to your GP covers how to have that conversation.