Daily Mail
LONDON
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.
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.
Drink water to reduce back pain
As many as 75 percent of us may be chronically dehydrated, according to US 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.