Nuts are one of the foods the Mediterranean way of eating leans on most, and they are also one of the most calorie-dense things in the cupboard. So how big should the handful be? The most-quoted answer is about 30 g a day. Use the tool below to see what that looks like for the nut you actually like.
The figure comes from PREDIMED, a large Spanish trial. People on a Mediterranean-style diet who were given about 30 g of mixed nuts a day (roughly half walnuts, a quarter hazelnuts, a quarter almonds) had fewer heart attacks and strokes than a low-fat comparison group. Observational studies also link regular nut eating with better health, though people who eat nuts often have other healthy habits too, so those studies show an association, not proof. Short trials find that nuts can lower cholesterol a little. See the sources at the end.
Thirty grams is about one ounce, or roughly 20 almonds. In the UK, average intake of nuts, nut butters and seeds together is only around 6 g a day, so most beginners are starting far below a handful.
Almost every nut lands between about 550 and 720 kcal per 100 g, so a 30 g handful is roughly 170 to 200 kcal. Walnuts, hazelnuts and macadamias are at the high end; cashews and pistachios at the lower end. That is not a reason to avoid them. Nuts are mostly unsaturated fat, and some of their energy is thought to stay locked in the nut structure, so the body may not absorb all of it. It does mean that a handful works best instead of something, such as a biscuit or a bag of crisps, and not on top of everything else.
Fibre differs more than calories: almonds and pistachios give noticeably more per handful than cashews. Peanuts are technically legumes, but they count in the same way in most guidelines.
Aim for about a small handful of plain nuts a day, in place of a less useful snack, not in addition to it.
Skip nuts you are allergic to; even small amounts can be dangerous. Whole nuts are a choking risk for children under five. This guide is general information, not medical advice. If you have a medical condition, are pregnant or breastfeeding, have or have had an eating disorder, or take medication, talk to a doctor or dietitian before changing how you eat. The research is also not a promise: a handful added to an otherwise poor diet is unlikely to change much on its own, because the benefit seen in studies comes from the whole Mediterranean pattern.