Calories in: having lunch in the garden
Losing weight is, in theory, a very simple process:
- If the calories burned off from exercise exceed the calories consumed from food , you will lose weight.
- If the calories consumed from food exceed the calories burned off from exercise, you will gain weight.
So all you have to do is exercise more and eat less.
Sounds easy, doesn't it? So why do so many people have problems losing weight? It's because it means breaking the habits of a lifetime.
Get Slim Quick: The Failure of Crash Diets
One of our worst habits is to fill our lives with all sorts of activities, some of which are trivial, and then when something happens that really matters, we go into crisis management and respond to it in the expectation that we have to get quick results. Such is the case of many people, especially women, who meet the partner of their dreams and decide they are more likely to be successful if they lose some weight, or they have made their catch and must lose some weight in the next few weeks to get into a reasonable sized wedding dress. So they go on a crash diet with the following consequences:
- The body uses up its reserves of fat as an energy source, but the metabolism slows down to make it last as long as possible. This is because we are designed to store fat when food is plentiful and use it up gradually when food is scarce. When you stop eating, the body thinks that food is scarce and goes into conservation mode. You feel weak and lethargic, and eventually become demotivated and start eating again, putting on the small amount of weight that you have lost.
- If you try to do some exercise while dieting, you will lose weight more quickly but the weight loss will consist of both fat and muscle, because you are not getting the nutrients required to maintain and build muscle mass. You will end up weak and feeble and will eventually become demotivated and start putting on weight.
Realism: Plan For The Next Year Ahead
To successfully achieve weight loss, you have go for moderate short-term results, followed by something more significant in about six months or a year.
If you live a sedentary lifestlye, sitting at a desk all day and doing no exercise, and then you start to do some exercise (for example going to a gym), you will start to lose some weight and will notice a difference in just a few weeks. This is because the energy balance (calories in minus calories out) has changed, but you won't continue losing weight indefinitely because the energy balance stablises at the new level. To lose more weight you have to look at your diet and try to achieve an energy deficit of about 500Kcal/day, which should cause you to continue losing weight at about 1 pound per week. However, it's a bit more complicated because losing weight is not the same as losing fat. When you do intensive or weight-bearing exercise, you can expect to build muscle, which is heavier than fat, so instead of losing weight you might gain some weight. So you can't measure your progress just by stepping on the scales, and in addition you have to take circumference or skinfold measurements to obtain your body composition. Normally you should aim for an increase in muscle mass and a loss of fat, and if the fat loss exceeds the muscle gain, there will be an overall loss of weight. In the end, you might decide that you have achieved your objectives when you look in the mirror and you like what you see, or you can get into some different type of clothes.
Balance of Nutrients
Whatever your objectives might be, you have to make sure the balance of nutrients is right, as follows:
- Carbohydrate should be your main source of energy, contributing about 50-55% of energy requirements, and is found in abundance in starchy foods such as potatoes, rice, pasta and bread. Carbohydrates are complex sugars that are gradually broken down into simple sugars, available for conversion to energy. They are classified according to their Glycaemic Index (GI) which is a measure of their complexity. The most complex carbohydrates have a high GI and the simplest sugars have a low GI. Carbohydrates with high GI are preferred for normal daily consumption because they break down gradually and keep us going throughout the day. Carbohydrates with low GI (sweets, chocolates, cakes etc.) tend to raise the blood sugar too quickly and contribute to fat storage, but they are preferred during or after prolonged exercise when the blood sugar is low and you need a boost. The calorific value of carbohydrate is 4Kcal/gm.
- Protein is essential for building and repairing muscles and other body tissues, but it is also an energy source and our total consumption of protein should be equivalent to about 10-15% of our energy requirements. Protein is available in meat, fish, eggs, dairy products, nuts, pulses and beans. It consists of long chains of amino acids, arranged according to the DNA of the plant or animal from which it came. When digested, it gets broken down into component amino acids and re-arranged according to our own DNA. Aren't we clever? We are digitally programmed to disassemble and re-assemble proteins according to our requirements. When we do intensive or load-bearing exercise, we cause small micro-tears in our muscles that get filled in with re-assembled protein from our diet, and that's how we build muscle, and that's why it's important to have some protein in our diet, especially if we are doing exercise. However, it's important not to have too much protein, because the excess is burnt off as energy and causes the blood to become acidic, dissolving calcium from our bones. The calorific value of protein is 4Kcal/gm, same as carbohydrate.
- Fat is essential for storing certain vitamins, namely A, D, E and K. It is present in a wide variety of foods, but especially fatty cuts of meat, full cream milk, butter, margarine, animal and vegetable oils, cakes and biscuits. Normally it contributes about 30-35% of our energy requirement, but if you are trying to lose weight you should try and reduce it to about 20%. Fat is made of triglycerides, consisting of three fatty acids combined with glycerol, an alcohol that has three hydroxyl groups. Saturated fats are those made up of fatty acids which have no double bonds in their carbon chains. They are solid at room temperature (for example lard) and they clog up the arteries and increase the risk of heart attacks and strokes. Unsaturated fats are those made up of fatty acids which have double bonds. They are liquid at room temperature (for example vegetable oil) and they keep the arteries clear. So it's good to have moderate amounts of unsaturated fat, while trying as much as possible to avoid saturated fats. The calorific value of fat is 9Kcal/gm, more than twice as much as carbohydrate and protein, so it's important not to consume too much. Also we have to take into account that fat goes easily into storage if it is not burnt off as energy.
- Alcohol has no nutritional value, but it has a calorific value of 7Kcal/gm. If you are feeling hungry and you drink some alcohol, you will still be hungry and you will need to eat something, so you get your calories twice over. That's why people who drink too much tend to get fat, and in men who get fat around the abdomen, it's known as the "beer gut". Alcohol also has the property of absorbing water so it causes dehydration. If you are already dehydrated from exercise and you drink alcohol, it will make the problem worse. It's a common practice for sports people to meet at the pub after a competition, but they always like to rehydrate with water and fruit juices first. By all means have some alcohol if you enjoy it, and it can help you to relax, but keep it in moderate quantities.
- Vitamins and minerals are known as "micronutrients" and serve a wide range of purposes. There are recommended levels of each of them, but it's quite complicated, trying to work out how to include them in your diet. Instead, the Food Standards Agency has categorised food types according to the Eatwell Plate Model, and if you stick to this you will get all the vitamins and minerals that you need.
Personal Training Programme
When you sign up for a personal training programme, for which nutrition is an essential component, I will ask you to make up a diet diary and an activity diary so I can see what you are eating and how you are burning it off as exercise. Then I will work out the energy balance and recommend changes that will result in a manageable energy deficit. At the same time I will try to identify any issues with the balance of nutrients and deal with them in order of priority, the most significant ones first. It takes time to change your lifestyle and eating habits, so we won't try to change everything at once.
Ideally, we should eat when we feel hungry and then stop, but if we like the food we tend to continue eating until we can't eat any more. We also eat for social and cultural reasons, for example people having birthdays and handing out cakes and biscuits. We tend to habitually indulge ourselves in festivities, against our better judgement, and it takes time to find out how to keep it in moderation and still enjoy ourselves. The social and cultural issues, and the lifestyle and habits are probably more complex than anything I have said about the science of physiology and nutrition, but if you are really serious about changing your life, you can sign up for the personal training programme and I'm sure I will be able to help you.
Calories out: London Marathon 2010,
crossing Tower Bridge