Saturday, 23 January 2010

Ghrelin, the other "in"

Having just written about Leptin, it's Ghrelin's turn now. When your stomach is empty, serum ghrelin level is high and when your stomach is full, serum ghrelin level is low. Interestingly, high serum ghrelin has a beneficial effect on the hippocampus (responsible for learning stuff) so do your studying when you're hungry!

As a full stomach reduces serum ghrelin and thus reduces appetite, anything that keeps the stomach full for longer reduces appetite for longer. This is where enterogastrones come in. The most useful one in terms of appetite control is cholecystokinin, the secretion of which is stimulated by proteins & fats. This is one reason why diets high in proteins & fats keep you full for longer. Another useful filler is fibre/fiber, of course. As shown on the BBC programme "The Truth about Food", blending a meal with water or some other low-calorie liquid like soup also slows stomach emptying.

Finally, sleep deprivation raises ghrelin so I must try harder to spend less time on my computer and get some shut-eye.

4 comments: said...

"Drinking very hot drinks also slows stomach emptying"

Really? I was not aware of that. In fact, I would think the opposite would be true. Can you cite a source?

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Nigel Kinbrum said...

Hi Jim.

A registered dietician told me that years ago. I think that he got it from Effect of test meal temperature on the gastric emptying of liquids, although Gastric emptying of liquid and solid meals at various temperatures: effect of meal temperature for gastric emptying says the exact opposite!

I'll remove that bit from my blog.


Barry said...

Hi Nigel

I am attempting to break the world record of 115 hours playing poker non stop.

I am allowed 5 minute breaks every hour which can be banked into longer breaks.

What advice can you give for me to eact and drink to 1) keep my engery levels up for so long and 2) reduce the need for toilet breaks?

Also, other than stimulents (caffine etc), sugar and alchohol, what should I avoid?



Nigel Kinbrum said...

Hi Barry,

That's an unusual request. As you're going to be mostly sedentary while playing, your body will be running on mostly fat (except for your brain, liver & red blood cells). To keep your brain happy, you want to maintain a rock-steady blood glucose level with minimal fluctuations.

To achieve this, I'd recommend that you eat meats, poultry, fish & oily fish (e.g. smoked salmon), cheese & eggs. These foods also contain virtually zero fibre, so you won't be needing a No. 2 for a few days!

As for fluid intake, I'd recommend that you drink either plain milk or weak milkshakes (assuming that you're not lactose intolerant), as the proteins will keep your stomach happy for ages and the slow-absorbing carbohydrate won't disturb your blood glucose level. They also contain virtually zero fibre.

You'll need a mini-fridge to keep all of this stuff in, unless you're allowed helpers.

Avoiding stimulants is wise, as when they wear off, you feel dreadful.

Good luck and let me know how you get on.

Cheers, Nige