The Body As a Battleground: Ghrelin and Leptin Duke It Out

I’m writing this from Danang, in Vietnam, where I’ve been on a whirlwind business trip. Three airports in three days: fly into Saigon, interview the CEO of the largest herbal-tea maker in the country; fly to Chu Lai to see their new factory using the latest aseptic technology from Germany; then fly out of Danang and back to Hong Kong.

Danang is on China Beach, where the American G.I.s used to take their R&R away from the front lines. The DMZ is just a few miles to the north.

At the end of my trip, I’m also getting some rest and relaxation. Only nowadays, my form of relaxation involves a session at the gym. I’m not inclined to sit around in a deckchair.

But first I had to eat. I stocked up for the day, nutrition-wise, with a big breakfast at the Hyatt Regency Danang. It’s quite a spread, as you often get at a five-star hotel, everything you could want and more.

Watermelon juice and coffee were the first orders of the day. Then, and as usual when there’s the hotel buffet on offer, I overdid it. Three plates later, I called it quits. Then I checked out their impressive gym, with lovely natural wood and light streaming in through the floor-to-ceiling windows. And gave the machines a whilr, a couple that were new tweaks on the old equipment in my “home” gym.

On the way back to the room, I felt downright queasy. It was all I could do to avoid throwing up.

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In Saigon, I had a much more sensible but still sizeable breakfast: dragonfruit, mango and guava; passionfruit-jam yoghurt; oatmeal, walnuts and chocolate buttons (as a treat); and Bircher muesli, named for the Swiss physician Maximilian Bircher-Brenner, who invented it for his patients in 1900. 

I realized there were two elements at play. First, I had eaten too much in the first place. Second, my “fight or flight” response had kicked in when I jolt-started my body in the gym.

There are two key chemicals that govern our appetite, the hormones ghrelin and leptin. They’re a pair, the yin and yang of your appetite.

Hormones act as messengers, sending signals to tell our body what to do. Ghrelin and leptin are the superstar hormones, the ones most often discussed by those who care about such things. And I have had first-hand experience here in Danang as to just how demanding and pushy they can be.

Ghrelin works directly on the brain to make you hungry. Your pancreas, kidneys and stomach cells release it when food and energy intake are low, telling your body to go out in search of sustenance. In our evolution, you might have had to fight to get it. After you eat, ghrelin goes down.

Leptin acts in the opposite way. It’s mainly secreted by fat cells. The more fat you have, the more leptin you have. When you have a lot of energy coming in, in the form of food, leptin goes up. And when it reaches its peak, we’re not hungry, telling our body it’s time to settle down and all to digest all the energy that ghrelin made you go out and get. It tells you that your tank is full.

They’re opposites. Ghrelin makes you hungry. Get up and go. Leptin shuts that down. Sit or lie down. Relax.

Your body has a 24-hour cycle for the release and absorption of leptin. It peaks between midnight and 4 a.m. if you sleep normal hours, and bottoms out around noon. That gets you ready for lunch.

Here in Danang, I loaded up on oatmeal, muesli, yoghurt, fresh fruit, coffee. Then I went for two eggs over easy, and some of the Vietnamese breakfast, cheun fan style blankets of white noodle flecked with mushroom, little ears of white noodle designed to soak up peanut sauce, sticky rice with bits of pork. Then I went back for more muesli, more yoghurt.

Then I worked out, a 40-minute burst of action, a bit of stretching and medicine-ball work first, then a spot of lifting, targeting my arms, chest, abs and legs. A bit of everything, just to get me going.

On the way back to my room, I soon started regretting my big breakfast. First of all, I didn’t need the sticky rice and noodles, let alone the second portion of muesli. But the breakfast buffet beckoned, and I couldn’t resist.

It is a good strategy to load up on carbs at the start of the day, as I’ve explained before. It gives you the stock of fuel you’ll need to burn for the rest of the day, easy-to-access energy that will keep you powered and more than likely prevent you from snacking or overeating later in the day. Have a smaller lunch and an even smaller dinner.

But it’s not a good idea to completely fill your belly at breakfast until it’s distending – and particularly then to work out. I initiated my “fight or flight” response that demanded an empty stomach just as mine was full. And I was loaded with leptin, telling me to lie down and take a break.

Apparently, the G.I.s in a different war made the same mistake before the Normandy landings on D-Day. Many filled up with the Big British Breakfast on offer. Some threw up in the landing craft taking them ashore. Others got on the beach and virtually couldn’t move, sitting ducks as they waddled ashore in their webbing. The ones who made it were fighting on empty stomachs, ready to sprint for cover.

Here in Danang, on the way back from the gym, my body didn’t know what to do. Run and fight, relax and digest, all of the above. And it decided the best option was to remove some of that sustenance from my stomach.

I avoided throwing up … I gave it a few moments, thought about waterfalls and peaceful wheat fields, and figured the moment would pass. It did.

There can be plenty of other reasons for feeling sick after eating, some of them serious. Food poisoning is an acute and obvious problem, debilitating and even dangerous. Luckily, I’m armed with an iron stomach, and the affliction has never struck me down.

You may instead have a food intolerance (you’ll know damn sure if you have an allergy – plenty of people mix up the two) to something you’ve eaten. There are eight main areas of concern: eggs, fish, shellfish, milk, peanuts, tree nuts, soy and wheat. Fortunately, I’ve escaped an intolerance or allergy to any of the above.

No, I had just eaten too much. Then supercharged my body and told it to race when it wanted to relax. It was confused, and told me to get rid of the excess food I was trying to absorb.

It was an instructive moment. I realized the power of the forces at work within our own bodies, ones that we should recognize and be cognizant of as we go about our day.

Particularly if you are interested in losing weight, or gaining muscle mass, the hormones and other chemicals kicking around our bodies are vital messengers telling it what to do. Ignore them at your peril – and use them to your advantage if you’re smart.

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