Why Diet Matters? 1) Hi again, welcome to our brief section about diet. We felt that diet was certainly worthy of mention in this course, although you won't find us preaching to you about what you should eat. The reason we've included this section is that when it comes to health and fitness, diet and exercise go hand-in-hand. We didn't have room in this pilot course to go in-depth into the subject of diet although if we receive feedback that this would be valuable, we will include a lot more content as we update the course I love this expression from Margaret Mead I came across that it's easier to change a man's religion than to change his diet. I can’t say I have tried to do either but it sounds like both are a bit of challenge. 2) As we saw in the section on exercise, if the amount of items for sale on Amazon is anything to go by, we do care quite a bit about both diet and exercise. There seem to be never ending stream of fad diets which promise all kinds of good things.
3) And of course we’re always hearing about our obesity crisis. At the moment there are more than 600 million people around the world who are obese and that represents around 13% of all adults. And it's easy to see that this figure is significantly higher than we saw in 1980 when just 6% of all adults were considered to be obese.
4) If the answer to the obesity crisis was simply a case of adopting a fad diet, we would have the problem solved by now but of course it is much more complex than that. Obesity is a bad idea as it increases the risk of all the major noncommunicable diseases, including type 2 diabetes, heart disease, stroke and several types of cancers— enough to decrease a person’s potential life span by as much as 14 years. Research shows that excessive weight also interferes with our body’s ability to fight off infections, sleep deeply and age well, among other problems. It is long past time for us to understand how to combat this epidemic.
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5) One of the interesting things that has come out of research is that when it comes to Weight Loss, exercise is not the most important thing to focus on. As we have seen though, exercise is still immensely valuable for health and for maintaining a healthy weight. We saw in an earlier section that it’s the volume of exercise that counts when it comes to health rather than intensity Research has shown that what you eat and how much you eat play a substantially greater role in determining whether you shed kilograms than exercise. It’s really important to note that Different people lose weight more effectively with different foods. 6) Losing weight can be reduced to a simple mathematical formula: burn more calories than you consume. For decades health experts used to believe that it did not matter too much how you created that deficit: as long as you got the right nutrients, you could safely lose weight with any combination of increased exercise and reduced consumption of food. But this assumption does not take into account the complexities of human physiology and psychology and so quickly falls apart when tested against real-world experience . As it happens, sorting out the details and putting weight management on a more scientific footing have taken much longer and have required a wider range of expertise than anyone had expected.
7) in order to understand the complexities, Science set out to discover the answer to a deceptively simple question How much energy does it take to fuel the average human body? This is not so easy to answer because each person’s metabolism - the efficiency with which we convert food to meet our energy requirements - varies a great deal from person to person.
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What we now know if that we do not need a lot of calories to stay healthy and active - and any excess consumption quickly results in weight gain
8) One of the things that might surprise us is how little difference our activity level makes to the rate at which we expend calories. If you compare someone with a sedentary lifestyle with someone who is highly active the difference in energy expenditure only amounts to about 200 cal per day. The significance of this is that our energy expenditure is not so clearly related to how much physical activity we carry out. 9) In essence we have essentially a fixed rate of energy expenditure. This means that dieting does not excuse you from exercise and exercise in general terms doesn't excuse you from the need to watch what you eat. The significance of this is the you have to exercise to stay healthy and vital and if you want to look after your weight you have to focus on your diet.
10) On average ,an adult male needs around 2500 calories per day and an average adult female needs 2000 cal per day. If we take an excess of just 50 to 100 calories per day this can lead to a weight gain of 1 to 3 kg over a year. You can imagine this turning into a weight gain of between 10 and 30 kilograms over a decade - pretty horrific - yes? So the bottom line is that exercise alone is not going to be enough to allow you to lose weight if that's one of your goals. Physical activity is responsible for only about one third of our total energy expenditure
11) Let’s go back to a point that was made earlier that the kind of food you eat is at least as important is how much you eat.
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12) Whilst calories are the commonly used way of describing foods, this tends not to be a good way of choosing which foods we should eat. So if we take this example of three foods each offering 100 calories, we can see that they contain different proportions of protein, fat and carbohydrates therefore they differ in their value to us. Science is just getting to grips with the fact that people can lose weight more effectively with some foods than others. How we metabolise foods varies from person to person. In addition, as anyone who has ever reached middle age understands all too well, metabolism changes over time. Older people need fewer calories to keep their body running efficiently than they did in their youth.
13) Let us suppose that you have started to lose some weight. Naturally, your metabolic rate and calorie requirements must fall as your body becomes smaller, meaning that weight loss will slow down. That is just a matter of physics: the first law of thermodynamics still applies. Studies show that metabolic rate drops somewhat more than expected during active weight loss. Once a person’s weight has stabilised at a new, lower level, exercise can help in weight management by compensating for the reduced energy requirement of a smaller body. The take away point is that a healthy diet and exercise are needed for health. In general terms, meals higher in protein or fibre, or those that do not cause a sudden spike in blood sugar levels, are generally more satisfying and better at suppressing hunger. When you suppress hunger you don’t eat so much. Carbohydrates are the most common source of glucose in the blood, but proteins can generate it as well. it is possible to reduce hunger during weight loss by choosing the right foods. For example, foods high in protein and fibre and low in glycemic index (fish, beans, apples, vegetables, grilled chicken and wheat berries for example. Ok thanks for listening - on to the next section.
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