Eat More Soup
It is the stuff of legend (and legions) that the Roman army marched on Minestrone soup. They knew what they were doing. When home made, and not out of a can, soup is not only good food, it will sustain you and also help you to lose weight.
But there's a physiological reason for this and it is called the...wait before I go on, because I have already told you, I am not dietician, so I think I'd better hand you over to Jack Challoner, who is a bit of an expert in the field and will explain all about the pyloric sphincter and a marvellous little hormone called the ghrelin. Take it away Jack...
How soup can help you lose weight
By Jack Challoner
In the battle to lose weight, hunger is the dieter's worst enemy. But research has revealed a simple aid to taming the appetite: soup. It's dieting's best kept secret says one science writer.
Imagine a typical lunchtime meal - say, chicken and vegetables with a glass of water.
If you eat the food and drink the water, you will feel full for a couple of hours before hunger kicks in. But if you blend the food with the water - to make soup - you will stay hunger-free for much longer, and less likely to snack through the afternoon.
How can blending the food into soup make such a difference? The answer lies in the stomach. Scientists have used ultrasound and MRI scans of people's stomachs to investigate what happens after eating solid-food-plus-water meals compared with the same food made into soup.
After you eat a meal, the pyloric sphincter valve at the bottom of your stomach holds food back so that the digestive juices can get to work.
Water, however, passes straight through the sphincter to your intestines, so drinking water does not contribute to "filling you up".
When you eat the same meal as a soup, the whole mixture remains in the stomach, because the water and food are blended together. The scientists' scans confirm that the stomach stays fuller for longer, staving off those hunger pangs.
The key to this low-tech weapon against hunger is a hormone called ghrelin. It is one of the major players in the body's appetite system.
Discovered as recently as 1999, ghrelin is released by specialised cells in the stomach wall.
These cells produce a constant stream of ghrelin whenever the stomach is empty. The ghrelin travels via the blood stream to the brain's appetite centre, an organ called the hypothalamus. As a result, the hypothalamus screams "You are hungry - find food."
But whenever the stomach wall is stretched - when the stomach is full - the cells stop producing ghrelin, and the hypothalamus responds accordingly, turning off the appetite signal. The longer the stomach remains full, the longer you feel satisfied and the less you are likely to eat.
The stomach gradually empties, more slowly for the soup than the solid meal plus water. The BBC staged an experiment for the programme 10 Things You Need to Know About Losing Weight to test this theory. In this experiment, and in previous experiments, participants reported feeling full for up to an hour-and-a-half longer than their solid meal counterparts.
Although some researchers refer to appetite as "the cupcake circuit", the mechanism behind human appetite evolved long before cupcakes were invented - at a time when food was scarce.
As a result, we are hard wired to eat high-calorie foods, which are unfortunately so abundant in the modern world.
Finding ways to control the appetite signal is crucial if we are to stave off the meteoric rise in obesity. Food scientists and pharmaceutical companies alike are on a major quest to find ways to do just that.
Appetite is one of the most researched areas of weight-loss science. Unfortunately, the appetite system is complex, and still poorly understood.
There are probably dozens of hormones that play a role in regulating appetite. Of those that have already been discovered, there is one that is released after eating protein-rich meals (called PYY), one that is released by fat cells (leptin) and several that respond to the presence of any kind of food.
But of all the hormones that make up the appetite system, it is ghrelin that has caused the most interest. In addition to its role in sending the "stomach empty" signal to the brain, ghrelin also promotes fat storage.
Even worse, it inhibits the breakdown of stored fat during times of weight loss. Inject ghrelin into the bloodstream of a rat and the animal eats insatiably - and quickly becomes obese.
In 2006, scientists at the Scripps Research Centre in the US developed a vaccine to counteract the influence of ghrelin, in an attempt to control appetite.
It is still undergoing clinical trials - so for now, the best and simplest way to keep hunger at bay is to reduce your stomach's release of ghrelin: blend your food into a healthy, voluminous soup. The best sort? Vegetable soup, as it produces a more consistent blend and is generally lower calorie than chicken or fish soup.
Jack Challoner is a science writer and author of the website explaining-science.co.uk.
THEY ALSO SAID:
"Bouillabaisse, this golden soup, this incomparable golden soup which embodies and concentrates all the aromas of our shores and which permeates, like an ecstasy, the stomachs of astonished gastronomes. Bouillabaisse is one of those classic dishes whose glory has encircled the world, and the miracle consists of this: there are as many bouillabaisses as there are good chefs or cordon bleus. Each brings to his own version his special touch."
"There is nothing like soup. It is by nature eccentric: no two are ever alike, unless of course you get your soup in a can."
Laurie Colwin, 'Home Cooking' (1988)
"Good soup is one of the prime ingredients of good living. For soup can do more to lift the spirits and stimulate the appetite than any other one dish."
Louis P. De Gouy, 'The Soup Book' (1949)
"Do you have a kinder, more adaptable friend in the food world than soup? Who soothes you when you are ill? Who refuses to leave you when you are impoverished and stretches its resources to give a hearty sustenance and cheer? Who warms you in the winter and cools you in the summer? Yet who also is capable of doing honour to your richest table and impressing your most demanding guests? Soup does its loyal best, no matter what undignified conditions are imposed upon it. You don't catch steak hanging around when you're poor and sick, do you?"
Judith Martin (Miss Manners)
"I live on good soup, not on fine words."
"Only the pure of heart can make good soup"
I like soup. I also like making soup. It is nutritious and will keep me full for longer. It is very economical and a great way to lose weight. It is also good for the soul. In fact, I don't just like soup. I love soup.