Green bananas, along with whole grains, vegetables and fibre, all contain resistant starch
What would a healthy diet based on scientific evidence look like? Rodney Bilton, emeritus professor of biochemistry at Liverpool John Moores University, has spent 15 years finding out - and discovered startling facts about what to eat to be slim and healthy...
Eat unripe bananas
Green bananas, along with whole grains, vegetables and fibre, all contain resistant starch. This is the most important form of soluble dietary fibre you can eat - soluble dietary fibre is not digested in the small intestine, but is absorbed more slowly further down in the body, where it is fermented by bacteria in the colon to give long-term energy.
Resistant starch is a carbohydrate but, unlike other carbs, its chemical make-up means that it does not cause your blood sugar to rise, so is not a risk for diabetes and it also doesn't cause sugar-crash hunger pangs after eating.
It also has another slimming advantage in that it stimulates the release of a hormone, glucagon, which boosts the rate at which our bodies burn fat.
Resistant starch is therefore a crucial dietary component for managing your weight and blood sugar, as well as helping healthy bacteria to grow in your large bowel, thereby reducing the risk of colon cancer.
Green bananas are the best source of resistant starch: the less ripe a banana is, the more resistant starch it contains.
In the Western world we eat on average between 3g and 7g a day of resistant starch. Expert bodies such as the Commonwealth Scientific and Industrial Research Organisation, the official science body in Australia, recommend eating at least 20g a day.
Don't mash your potatoes
Keeping our intake of sugar as low as possible is important for both our waistlines and our general health. While the obvious thing to do is to cut out sugary drinks and processed foods, we should also consider how we prepare healthy foods in the kitchen.
The way we cook food can alter the amount of sugar released into the blood. For example, 25 per cent more sugar is released from a potato when it is boiled and mashed before eating, compared with cutting it into chips.
Potato and other carbohydrates contain large granules of starch. Heating and grinding - eg, mashing or pureeing - starch granules increases the amount of sugar by breaking open the membrane that surrounds them, releasing starches that turn into sugar.
Heating and grinding - eg, mashing or pureeing - starch granules increases the amount of sugar
Anything like this that you do to a food, such as grinding, pressing and even chewing, accelerates the rate at which the sugar is released into the blood. It increases the surface area of the food - making it easier to absorb and increasing the rate of digestion in the intestine.
Similarly, eating an apple whole releases less sugar into the blood than apple puree, which in turn releases less sugar than drinking apple juice, according to a study in The Lancet.
When cooking a food such as potato, the heat and the amount of water used also have significant effects on the amount of sugar released, the same Lancet study found. The more a starch-containing food such as potato is heated, loaded with water and mashed up, the more easily it will be digested, releasing its sugar into the small intestine.
And the less manipulated or refined a food product is, the less sugar is released when it is digested. So baking or frying a potato means it will release less sugar than if mashed.
Add water when you fry
Most of us cook with oil, but over heating can break down cooking oils, producing toxic chemicals called lipid peroxides. When eaten, they can react with proteins and DNA - your cells' genetic blueprint - in ways that are believed to increase the risk of cancer and heart disease.
Olive oil, particularly extra virgin oil, is best used as a salad dressing and not in cooking, because it starts to burn at a comparatively low temperature and therefore breaks down easily.
When frying, a good tip is to emulate the Chinese and add a small amount of water to the wok or frying pan. This lower s the f r ying temperature of the oil to 100c and reduces the amount of oxidative damage to the fat which normally occurs
Drink water to reduce back pain
As many as 75 per cent of us may be chronically dehydrated, according to U.S. research.
This not only affects our waistlines, but our backs, too. Preliminary research suggests that drinking eight to ten glasses of water a day could significantly ease back and joint pain for up to 80 per cent of sufferers. This is because being dehydrated makes the blood and joint fluids thicker; it also causes crystals of uric acid (a bodily waste substance normally removed in urine) to form in the joints, which can cause gout-like pain.
Drinking water is also a valuable and painless aid to weight loss. Even a mild state of dehydration will slow our metabolic rate by as much as 3 per cent and may play a role in weight gain.
And every drop of water consumed involves calories being used as the kidneys work to remove the excess water from our bodies. Moreover, drinking water shortly before bedtime has been found to prevent midnight feelings of hunger for nearly 100 per cent of people who were tested, according to Washington University cardiologist, Dr Stephen Sinatra, in his book Optimum Health.
Drinking five glasses of water daily can reduce our risk of colon cancer by 92 per cent, according to a study in the International Journal of Cancer in 1999. Good hydration lubricates our bowels and causes them to move faster.
This reduces the amount of time that potentially carcinogenic waste products stay in our colon. The same amount of water has been suggested to cut the risk of bladder cancer by 49 per cent, and of breast cancer development by almost 80 per cent.
Good hydration increases blood flow through the liver, helping the body to remove potential carcinogens, which is why it is believed to reduce the risk of bladder and breast cancer.
Vegetarians who consume tofu and bean curd as a total substitute for meat put themselves at risk
Why you should beware of tofu
Vegetarians who consume tofu and bean curd as a total substitute for meat put themselves at risk of mineral deficiencies because they usually ignore a simple lesson on the way these foods are eaten in Japan.
These products are made from soy beans high in a substance called phytic acid. This can block absorption of essential minerals such as calcium, magnesium, copper, iron and especially zinc.
Many scientists agree that diets high in phytates derived from soy have contributed to widespread mineral deficiencies in Third World countries, even in areas where minerals are not in short supply.
The Japanese avoid this problem by eating tofu alongside soy bean products such as miso (a thick paste used for sauces and spreads) and natto (a strong-smelling, sticky bean product), which have been fermented with strains of the bacterium Bacillus subtilis. These bacteria lower the phytic acid content of these foods.
Some vegetarians tend to get protein from processed sources such as vegetarian sausages, burgers and other textured protein foods.
Any processed foods labelled as containing vegetable oil will invariably contain partially hydrogenated fats - and traces of transfats - and should be avoided because studies have shown that they increase the risk of diabetes, heart disease and cancer.
Eat like a Masai tribesman
For a long time we've been told that too much fat - particularly saturated fat - is bad for health. As a result, many people have tried to reduce the amount they eat.
This has led to a rise in the consumption of refined carbohydrates, such as white rice, pasta and bread, which can be linked to a sharp rise in obesity - primarily because refined carbs leave us wanting more.
Fat is better at making us feel full - and feel full for longer.
We respond to low-fat regimens by modifying our diets to eat the amount of calories that make us feel satisfied and which will support our daily energy requirements. Thanks to the low-fat diet myth, we have all gradually increased our intake of carbohydrates to replace the energy lost from consuming less fat.
Furthermore, meals high in fat promote the release of the hormone glucagon from the pancreas. Glucagon promotes the breaking down of body fat for several hours after a meal is eaten. This benefits those wishing to slim.
Many human populations eat large amounts of fat and remain perfectly healthy. East African tribes such as the Masai and the Samburus consume up to 400g of animal fat daily. In Britain, 60g a day is thought healthy.
The tribespeople show low cholesterol levels and an absence of heart disease. When populations of such people migrate to other areas where refined foods high in carbohydrates are consumed, their levels of so-called 'bad' LDL cholesterol rise.
The real danger of smoothies
Our bodies have only a limited capacity to deal with high levels of fruit sugar
Our bodies have only a limited capacity to deal with high levels of fructose - the fruit sugar found in fruit juices and smoothies, and in high-fructose corn syrup, used as a sweetener in store-bought biscuits, cakes, ice creams and drinks.
That's because it sneaks past the insulin system.
High intake of fructose bypasses the body's normal processes of controlling the amount of sugar in the bloodstream - the body produces the hormone insulin to use or store the glucose it gets from food. But high levels of fructose don't stimulate the body to produce insulin and hormones that suppress appetite.
As a result, fatty substances can build up in the liver, causing them to become enlarged and inefficient, leading ultimately to obesity and type 2 diabetes.
PS... The only diet tip you really need
Understanding how to combat hunger is far more beneficial to slimming and a healthy diet than calorie-counting. Hunger is effectively reduced by modifying your diet to increase the digestion time - this is because the human digestive system has evolved to efficiently and rapidly extract every available calorie from diets that, in caveman times, were often poor in nutrients.
Our digestions can't work so quickly with nutritious protein and fat. The feeling of hunger following a meal high in protein and fat returns much more slowly than with other diets because fat and protein are digested more slowly and remain in the stomach for longer. Simple.
Know What To Eat, by Dr Laurence Booth and Professor Rodney Bilton, is published by Supercritical (£9.99). See knowwhattoeat.com
Read more: http://www.dailymail.co.uk/health/article-2692057/Dont-eat-mash-dont-cook-olive-oil-DO-eat-unripe-bananas-Think-know-rules-healthy-eating-A-scientist-lots-surprises.html#ixzz37UjXEmCz
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