Healthy snacks for work: which, when and how much.

Twenty to eleven, between two calls, and your stomach is rumbling. Healthy snacks for work were the plan on Sunday night, but the desk drawer holds crackers and the vending machine is down the corridor.

People often ask me what to eat mid-morning. Whatever you already have with you. So I'll start with the places, and the portions.

Quick healthy snacks: what to keep, and where

The formula. Protein, plus fibre or good fats, in a portion that fits in your palm. Sweets and crackers on their own send your blood sugar up fast, and about two hours later hunger can be back. Fruit alone fills you only briefly too, because fructose leaves your hunger hormone switched on. With a few almonds it lasts longer.

• In the drawer. Plain walnuts and almonds, in their shells if you can. Cracking them slows you down and you eat fewer. One handful.
• In your bag and in the car. A handful of nuts portioned at home and a whole piece of fruit, eaten together.
• In the office fridge, your high-protein healthy snacks. A pot of Greek yoghurt, with about twice the protein of an ordinary one. Or a boiled egg, or a small piece of hard cheese with carrot sticks.
• At the café and the airport. A plain yoghurt, a small piece of cheese with fruit, or a small egg or chicken sandwich. Real yoghurt has two ingredients, milk and live cultures. Fruit ones can carry more than three times the sugar.
• At the vending machine. In this order: water, plain nuts, plain yoghurt. Crackers feel light, but weight for weight they have about 30 per cent more calories than bread. Juice and iced tea are sugar you drink.

Do I need a mid-morning snack?

After a proper breakfast, often not. You need one if your last meal was light or skipped, or if the next one is far off.

When you need one, and at what time. With many hours between lunch and dinner, mid-afternoon. If you train after work, about two hours before, and light. Under heavy stress, make it fibre-rich: it can help keep your blood sugar steady.

Between meals your body gets on with its work. Does eating often 'fire up your metabolism'? The idea holds up poorly. Every time you eat, insulin rises, and while it's high your body tends to draw little on its fat. With four hours or more between meals, the hormones that release fat have room to work. And six mini-meals can keep hunger switched on.

Hungry? Think back to your last meal

• It's been less than three hours. Often it's thirst, or wanting a break. Water first.
• Breakfast was all sugar. Toast and jam or a pastry leaves you running on empty. The thing to fix is breakfast.
• Lunch was a sandwich on the run, or it never happened. This hunger is real. Have a snack with protein.
• It turns up at the same time every day. That's usually habit. You're after the break.

Start with the drawer: crackers out, walnuts in. And when hunger arrives at eleven, think back to breakfast.