I usually lose a week to jetlag. This time I lost a kilogram instead.

For most of my career I have flown long-haul badly. Three weeks to recover. Two hours of sleep a night for the first week. A pattern of falling into deep sleep on landing and waking at two in the morning wide awake, then spending hours trying to get back to sleep.

The other reliable feature of a conference trip is the kilo or two I bring home. I do not drink. I am disciplined about food at home. None of that has ever protected me from a week of hotel breakfasts, conference morning teas and lunches, and restaurant dinners every night.

This month I flew to London for a week. The International Women's Forum cornerstone conference. I came back without jetlag and a kilogram lighter than when I left.

This is the first time I have done that. The difference was not a new piece of knowledge I had picked up. The difference was that I put the problem to AI and did what it told me to do.

The outbound flight

The instinct on a long flight is to sleep when you can. AI told me that was wrong. Flying west, sleeping on Australian time after midnight just deepens the misalignment when I land. I needed to build sleep pressure and then release it in a narrow window timed to London night, not Adelaide night.

I had six hours of sleep on the entire journey to London. All of it in the second half of the Singapore to London leg. On previous trips I had slept in the first half of that leg. This time I had to stay awake through it.

Staying awake in a dimmed cabin while everyone around me slept was not easy. The thing that worked was light. Bright entertainment screens directly in my line of sight. Light therapy glasses on. I have used the glasses on previous trips and they made little difference. This time I used them the way AI told me to, layered with the screens, for the right window, on the right leg. That was the part I had been getting wrong.

When I finally let myself sleep, I dropped into deep sleep almost immediately, with a sleep mask and earplugs. I had built so much sleep pressure that the cabin disappeared.

I ticked the box on the cabin card asking not to be woken for breakfast. I uploaded the breakfast menu to AI before the flight in case I did wake. My instinct was the muesli, yogurt and fruit. I thought that was the healthy choice. AI said no. Sugar from the fruit and refined carbohydrate from the muesli would spike my blood glucose, drive an insulin surge, and drop me into a slump within two hours of landing. It told me to order the poached eggs with the potato rosti, but not to eat the rosti. Clean protein. No starch sitting in my system for the next eight hours. I realise the privilege of flying business class gave me menu options and a flat bed, but on every previous trip neither had been enough to spare me the jetlag.

I woke a couple of hours out of London. I had the eggs.

The week in London

Coffee before midday only. That sounds minor. It was the rule that surprised me most.

At home I already avoid coffee after midday. But on every previous trip, when the three o'clock afternoon slump hit in a conference room, I used one or two strong coffees to power through to the evening. I thought I was solving the problem. AI told me I was causing the two-a.m. morning wake-up. Caffeine has a five to six hour half-life. An afternoon coffee is still circulating at ten at night. It does not stop me falling asleep. It fractures the sleep I do get.

The replacement for the afternoon coffee was light. Glasses back on for forty-five minutes at around four. That holds off the evening melatonin surge long enough to get through dinner.

The same logic applied to food. On previous trips I had reached for something sweet in the afternoon. AI explained why that was the worst possible choice. Sugar in the afternoon drives an insulin spike, then a reactive low two to three hours later. The body reads that low as an emergency and releases cortisol and adrenaline to push blood sugar back up. Those stress hormones do not switch off when the sugar normalises. They are still circulating at two in the morning, which is when I would wake up wide awake and unable to settle. Lean protein and vegetables at lunch keeps blood glucose flat, keeps me alert through the late afternoon without a crash, and does not set up the rebound that wakes me in the night.

During my London stay, before every business lunch and dinner I uploaded the restaurant menu to AI and worked out what to order before I sat down. Fish. Green vegetables. Sauces on the side.

The flight home

I deliberately under-slept the night before the return flight to build a sleep debt for the plane. In the Heathrow lounge two hours before boarding, smoked salmon and eggs with no muffin and no pastries.

The moment the plane took off at midday London time, I reset my watch to Adelaide time. Twenty-five past nine at night. Time to sleep. Loose clothing. Compression stockings. Eye mask. I slept across the Adelaide night (and London day).

Two hours before Perth, the in-flight breakfast was my morning. Poached eggs on spinach. No toast. No sauce. Strong coffee with very little milk. The transit walk in Perth airport was deliberate and brisk, in the brightest light I could find, to signal full daylight to my body.

On the final leg to Adelaide I had a 5pm crash. Eyes closing. Every previous trip I would have reached for sugar or a coffee. AI had told me what to do instead. I drank ice cold water to stimulate the vagus nerve, sat fully upright, and did thirty hard ankle pumps to push blood back up to my brain. It worked. I stayed awake. I landed at six. I was home by seven. I stayed up until ten.

The second night home and the oat slice

I slept solidly the first night. The next evening was the trap.

I wanted an early dinner at five o'clock. AI flagged the problem. Eating at five and then nothing until breakfast was a fourteen-hour fast across the night. Blood glucose would drop, cortisol would rise, and I would wake at two. Same mechanism, different cause.

It told me to eat something else at nine, but to engineer it carefully. Slow-release carbohydrate. Protein. No sugar.

I make a baked oat slice from my cookbook, The No Recipe Cookbook. AI varied the recipe. Maple syrup and Greek yogurt instead of honey. Wholemeal flour instead of plain. Nuttelex instead of butter. A quarter of the flour replaced with protein powder. Almonds folded through, for the magnesium, which relaxes muscles and supports the brain chemistry of deep sleep. Frozen blueberries for the polyphenols, which calm joint inflammation after long hours sitting still, and to keep the slice moist while it baked. One slice at nine.

I slept through the night.

What I take from this

I had thought I knew how to manage long-haul travel. I had used light therapy glasses before. I had read about sleep hygiene. I had been careful about food.

I did not know that the afternoon coffee I used to fight jetlag was the thing keeping me awake at two in the morning. I did not know that sugar in the afternoon would make me sleepier rather than more alert, and that the rebound from it was the same mechanism that woke me in the night. I did not know that the way I had been using the light therapy glasses was wrong. I did not know that a protein-only plane breakfast was different in any meaningful way from muesli and fruit.

I knew enough to think I was managing it. I did not know enough to actually solve it.

What changed this trip was that I stopped trying to figure it out on my own. I put the problem to AI and it told me, with the physiology behind every instruction, what to do at every decision point. I followed it.

The result was the first international trip that I did not have to recover from.