The 4pm Crash

Four o'clock, and you want something sweet and a coffee. You're not hungry. You're flat.

Some of that dip happens biologically due to the time of day, as body temperature and alertness fall in the early afternoon on a normal circadian rhythm. However the depth of it is dug by what you do earlier.

If breakfast was cereal, toast or a pastry, and lunch was a sandwich and a packet of crisps, you've had two large doses of refined carbohydrate with very little protein. Blood glucose climbs, insulin brings it back down, and the trough lands perfectly timed with that biological afternoon dip. Add a night of under six hours' sleep and you've got the 4pm crash.

Three changes, in the priority order.

Put 30 grams of protein at breakfast. Eggs, Greek yoghurt — Skyr or Fage 5% rather than the low-fat stuff with fruit stirred through it — leftover chicken, or a protein shake with a banana if the morning has got away from you. Protein blunts the glucose response of everything eaten alongside it and keeps you full for hours rather than ninety minutes.

Do the same at lunch. Keep the bread if you like bread — add the protein rather than removing the carbohydrate. A sandwich with 30 grams of chicken in it behaves very differently from a sandwich with a scrape of something in it. This is how Dr Amy likes to get her clients to think, often addition > subtraction.

Then walk for ten minutes after you eat. A short walk after a meal measurably lowers the glucose peak.

If you do want something at four, make it protein-led rather than sweet. Greek yoghurt, a handful of nuts with an apple, a boiled egg, leftover chicken, or maybe this is the time for your protein shake. A biscuit or sweet treat will just start a second dip in an hour or so.

What about coffee? Caffeine has a half-life of five to six hours, so the 3pm cup is still half in your system at 9pm and a quarter of it at 2am. If the afternoon dip is being managed with caffeine and the sleep is then poor, you've built a loop. Cut coffee off at midday for a fortnight and see what happens to both ends of it, be ready for the first few days to feel crap though!

Sort breakfast first. The rest of it follows. Remember, breakfast doesn't need to be before work, it just marks your first meal of the day.

If food is the bit you've never had any help with, our Nutrition and Lifestyle Programme is run by Dr Amy George — a CrossFit coach and an HSN nutrition and lifestyle coach. No meal plans, no rules to break. Book a free, no-obligation 15-minute chat with Jeremy or Beth at crossfitchiltern.com.