rates continue to climb, nutritional scientists in labs around the
world are trying to answer the question: what fills us up?
‘How we can
become satiated on good foods – in other words, eat less and feel
less hungry – has become the big question,’ says obesity specialist
Dr Alex Johnstone, of the Rowett Institute for Nutrition and Health
And where the
scientists tread, food and supplement manufacturers soon follow.
£45 million last year on ‘satiety’ products designed to fill
your gut and quell your appetite.
One of the
first retailers on the satiety bandwagon was M&S, which early
this year launched the Feel Fuller For Longer range based on Dr
Johnstone’s work. The meals are high in protein, which is filling,
but not high in calories.
‘It’s one of
our most popular launches because it’s an easy way to plug the hunger
pangs that usually lead to diets failing,’ says M&S nutritionist
foods can plug the gap just as well; as shown by research from San
Diego University’s School of Exercise and Nutritional Sciences,
which compared the feelings of fullness generated by eating plums
and biscuits – and the plums, surprisingly, won hands down.
Two hours after
eating, the volunteers given the plums felt less hungry and had
less of the ‘hunger hormone’ ghrelin in their blood when tested.
taking commercial appetite suppressants may not work as well as
the right foods.
The irony is
that we shouldn’t actually need to worry about satiety because as
babies and toddlers we are very sensitive to satiety cues and ‘tend
to stop eating when the biological signals kick in’, explains Marion
Hetherington, professor of biopsychology at Leeds University.
‘But that sensitivity
starts to decrease from the age of around three.’ This is when the
parental pressure to ‘eat it all up’ is applied and food is offered
as a reward between meals, displacing internal cues.
‘programming’ may also explain why bottle-fed babies – urged by
mothers to drain the bottle – learn to override their satiety signals
and put on weight more quickly, according to Child Growth Foundation
As we get fatter,
we have lower levels of a key ‘full-up’ hormone in the brain, known
overweight decreases PYY, so the satiety signals are slower to kick
in,’ says Dr Rachel Batterham, who carried out the original research
on the hormone.
who runs the weight-loss clinic at University College Hospital London,
has shown, through brain scans, that being overweight depletes PYY
production, and blunts the pleasure systems in the brain.
more sugary and fatty food is needed to get the same pleasurable
sensations from eating. And when overweight people diet, their level
of the ‘hunger hormone’ ghrelin shoots up (a survival mechanism
to give their heavy bodies the energy they demand), making them
more hungry, adds Dr Batterham.
But high satiety,
low-calorie foods can help. Here we look at the latest evidence
on how you can trick your body into thinking you are full.
Fruit and veg
contain a lot of water, air and fibre which pack your gut, producing
‘filling’ signals in the small intestine. Apples, for example, are
about 25 per cent air and, as they’re digested, they produce the
hormone GLP-1, which sends satiety signals to the brain.
The trick is
to eat high-satiety foods at the beginning of a meal. ‘They get
you to feel fuller early on and the evidence shows you don’t compensate
for this later by eating more,’ says Robert Welch, professor of
food science and nutrition at Ulster University.
You may not
fancy kicking off a meal with a plateful of diced apple – and no
restaurant would offer it – but the next best option is a salad,
for similar reasons.
the most satiating of the three food groups (compared with carbohydrates
It is why the
high-protein, high-fat Atkins diet works: despite the fat, you can’t
eat a lot of protein before your stomach says stop.
British diet is about 15 per cent protein, which is adequate for
growth, tissue repair and maintenance, says Dr Johnstone. ‘But if
you increase that to around 20 to 30 per cent of your calorie intake,
you’re going to increase satiation significantly.’
So what makes
protein so filling? It triggers the production of the ‘full-up’
PYY hormone in the brain, and sparks the release of glucose in the
small intestine; both send out satiety signals.
It is why,
traditionally, the main course in a meal is protein-based.
of food and, in particular, how glutinous or viscous it is, can
make all the difference to how full it makes you feel. That’s why
soup is a high-satiety food.
with a plate of food and they may be hungry three hours later; pulp
the same ingredients into soup and the ‘satiety’ period lengthens,
despite the decrease in the volume of food you’re eating, says Professor
from Sydney University working on a ‘satiety index’ of foods found
that its viscosity makes porridge twice as filling as muesli, even
though the main ingredient is the same.
pre-dinner nibbles, such as crisps – dry and high calorie – are
a bad bet. You need to consume four times as many calories from
crisps as you do from boiled or pureed potatoes to feel equally