BBC - KS3 Bitesize Science. These are the processes that happen in the digestive system: ingestion (eating) . Now we will look at how the products of digestion are absorbed into the body. Absorption. Digested food molecules are absorbed in the small intestine. This means that they pass through the wall of the small intestine and into our bloodstream. Once in the bloodstream, the digested food molecules are carried around the body to where they are needed. Only small, soluble substances can pass across the wall of the small intestine. Large insoluble substances cannot pass through. Study the slideshow to check your understanding of this. Absorption into bloodstream. The inside wall of the small intestine needs to be thin, with a really big surface area. What is the Fast Diet? It may be radical, but the Fast Diet is also wonderfully economical with its rules. All you really need to know is that.This allows absorption to happen quickly and efficiently. If the small intestine had a thick wall and a small surface area, a lot of digested food might pass out of the body before it had a chance to be absorbed. To get a big surface area, the inside wall of the small intestine is lined with tiny villi (one of them is called a villus). These stick out and give a big surface area. They also contain blood capillaries to carry away the absorbed food molecules. Egestion. Excess water is absorbed back into the body in the large intestine. What is left then is undigested food. This is stored in the rectum, the lower part of the large intestine, until we are ready to go to the toilet. It then comes out of the rectum through the anus as faeces. This process is called egestion. The 5: 2 diet: can it help you lose weight and live longer? Several months ago I set myself an ambitious goal: to find a way to live longer, stay younger and lose weight. I also wanted to go on enjoying the foods I normally eat and make as few changes to my lifestyle as possible. After talking to several scientific experts, I have spent the past few months trying a controversial diet that challenges conventional views about how and when we should eat. It is called intermittent fasting – reducing your food intake on alternate days. When crash- dieters give up, as invariably they do, they pile on the pounds, mainly as fat. It is known as yo- yo dieting and does you no good. At this year’s event there were more than 7,0. The most impressive competitor, however, had to be Fauja Singh, also known as “the turbaned tornado”. At 1. 01, he is the world’s oldest marathon- runner. The Fast Diet by Dr Michael Mosley and Mimi Spencer at the Telegraph Bookshop. His lifestyle is nothing like that of the average marathon- runner. He is a strict vegetarian, so he is not getting muscle- building protein from fish or meat. He also eats much the same thing every day — he lives mainly on lentils, vegetables garnished with ginger, brown bread, fruit and yogurt — and his portions are tiny (no carb- loading for Fauja). Which explains his weight. He is 5ft 8in tall and weighs just 5. Scientists have known since the Thirties that one of the best ways to extend life is to eat a nutritionally rich but calorie- restricted diet. Mice on such a diet live up to 4. Fortunately, there is an alternative that seems to offer many of the same benefits — intermittent fasting. When I visited him for BBC Two’s Horizon, he showed me a remarkable little mouse that had been genetically engineered to live longer. These mice hold the record for longevity extension in a mammal.” The average mouse has a lifespan of about two years. Laron mice can live for up to five years. Like his genetically engineered relatives, he should live to the equivalent of 1. Oddly enough, when the mice are examined, scientists are often unable to find a cause of death. The heart just stops. As Prof Longo explained, IGF- 1 and other growth factors keep our cells constantly active. Many of the changes in my body when I took part in the clinical trial of an intermittent fasting diet were no surprise. Eating very little for five days each month, I. A new eating plan that involves 2 days of dieting each week is being promoted as the key to. The Atkins diet, also known as the Atkins nutritional approach, is a low-carbohydrate diet promoted by Robert Atkins and inspired by a research paper he read in The. Please note, the Healthy Diet Plan newsletter is completely separate to BBC Good Food’s regular weekly newsletter. All health content from BBC Good Food is provided. It’s like driving along with your foot hard on the accelerator pedal. The evidence for this comes not just from animals such as the Laron mice, genetically engineered so that they don’t respond to IGF- 1, but also from humans. It is incredibly rare: fewer than 3. Like the mice, people with Laron syndrome don’t respond to IGF- 1. They are short, typically less than 4ft tall, with prominent foreheads and underdeveloped jaws. Prof Longo thinks this may be because they have learnt that they are naturally resistant to cancer and diabetes, and tend not to be terribly careful about their diets. The reason seems to be that when we run out of food our bodies change from “growth” to “repair” mode. But Prof Longo warned me that fasting is not for the faint- hearted, and is safest done in a specialised centre or under supervision. It’s not common but it happens.” I started my fast on a Monday evening, after a final slap- up dinner of steak, and finished it after more blood tests on the Friday. During that time I drank black tea, black coffee and lots of water but consumed no food. But what I found was that, after the first 2. I had hunger pangs, but they passed. Prof Longo warned me, however, that to maintain these benefits I would have to change what I ate. Foods such as meat and fish are rich in protein, but so is milk. A skinny latte, which I drink most mornings, comes in at around 1. Recommended levels are a relatively measly 5. But it is also tough for someone like me who enjoys their meat. Prof Longo is pretty much a vegan. I was prepared to give up lattes but not to go that far. We ate burgers and fries while she told me about a diet that she has been testing on human volunteers. It’s called Alternate Day Fasting (ADF) and is very simple. One day you eat whatever you want. The next day, you fast. On Dr Varady’s fasting days you are allowed about 6. The real surprise was that on my “feed days” I could eat exactly what I wanted. One group were put on a low- fat diet on their feed days, while the other were encouraged to eat lasagnes, pizza — a typical American high- fat diet. As Dr Varady explained, the results were unexpected. But they did. People on the high- fat diet were losing as much and sometimes more weight, week after week.” And it wasn’t just weight loss: the groups saw similar falls in LDL cholesterol — “bad cholesterol” — and blood pressure. Dr Varady is running a year- long trial to assess the longer- term effects of ADF on weight loss and health. She is keen to see how much her volunteers lose and how many will still be on the diet after a year. With this regimen you eat what you want five days a week, then twice a week you restrict yourself to just 6. I decided to try different approaches, to see what would work for me. The trouble is, I hate starting the day hungry. So then I tried a large breakfast and nothing else. I got really irritable in the evenings. A typical breakfast now means two scrambled eggs and a slice of ham (quite a lot of protein, but well within limits), with plenty of water, green tea and black coffee to see me through a working day. Then, in the evening, I tuck into something like grilled fish and lots of vegetables. It is impressive how few calories there are in vegetables, and when you are hungry they are unexpectedly delicious. It is reassuring, when you are on a restricted- calorie day, to know that the next day you can eat whatever you want. The surprising thing is that you don’t. Dr Varady said that her team expected people to gorge on their feed days, but most people are happy to eat their normal diet. Such is the power of habit. The results were impressive. I had lost well over a stone, down to less than 1. My blood glucose, which had been borderline diabetic, was normal and my cholesterol levels, previously high enough to necessitate medication, were also down in the healthy range. I look better and I feel good on it. I still sometimes eat burgers, biscuits and cakes, but on my fasting days I eat healthily. It will not suit everyone, nor is it safe for everyone. It worked for me and I will keep doing it. Or I think I will. We shall see. To watch his BBC Two Horizon programme on intermittent fasting, go to the BBC i. Player (bbc. co. uk/iplayer) or visit tinyurl. BBCHorizon. Fasting The 5: 2 diet: what is it and how does it work? On the two “fasting days” you eat 5. For a typical 3. 00- calorie lunch or dinner, try grilled fish or meat with vegetables. Most dieters, rather than feeling a need to gorge, found that they were happy to consume around 2,0. It can reduce levels of IGF- 1 (insulin- like growth factor 1, which leads to accelerated ageing), switches on DNA repair genes and reduces blood pressure, cholesterol and glucose levels. As a diet, it is not recommended for pregnant women or diabetics on medication. Anyone considering a diet that involves fasting is advised to consult their GP first, and to do it under medical supervision.
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