The Elements of Nutrition
The Big Picture on Nutrition
There is considerable truth in the adage 'You are what you eat'. The state of your body and how well it works depends to a large extent on how appropriately it is nourished. Malnutrition can be found in contemporary Western society and is not peculiar to developing countries.
Malnutrition occurs when a person's body is not adequately serviced by its food intake. Each individual's needs change under different circumstances. Moreover, the foods needed by an athlete, a grandmother, a growing boy, an office worker or a pregnant woman are not the same. Nutritional needs vary even from one office-worker to another, according to genetic make-up, level of activity, general state of health and environment.
Some groups of people who are at risk from nutrient deficiencies can be generally identified. These include those who are socio-economically disadvantaged; women during the reproductive years because of the added nutritional demands of menstruation and of pregnancy; the elderly; those who have a particular health problem, such as diabetes, faulty absorption of food or who are on certain medications; those with lifestyle problems such as cigarette smoking and alcohol abuse.
The nutrients in food are used by our bodies in varying ways. Each nutrient plays some part in normal body function (that is, body physiology).
Not all components of food are nutrients, and not all nutrients are essential to life. Some nutrients may have important physiological functions without being absorbed from the gut, for example dietary fibre. Dietary fibre, while not being essential to life, is associated with health because of its role in the correct functioning of the bowel. Its absence may increase the risk of bowel disease.
Although recommendations about nutrient intakes are made in terms of daily intakes, not all nutrients are needed every day. Most can be stored to a lesser or greater extent in our bodies. The macronutrients that provide energy are stored in the liver and muscles in the form of a carbohydrate called glycogen, and in fatty tissues (adipose tissue) and muscles in the form of fats, known as triglycerides. The situation for micronutrients varies. Fat-soluble vitamins, such as vitamin A, tend to be stored in liver and fat and do not need to be replenished every day; they can last for weeks if the stores are good. In general, water-soluble components like vitamin C are quickly excreted in the urine. But some water-soluble nutrients such as vitamin B-12 and folacin (folic acid) can be stored for years and months, respectively, in the liver. Some nutrients, for example calcium and phosphorus, are in effect stored in bone.
Energy Balance
If you eat more than your body needs to keep it working efficiently, you will get gain excess weight. Many slimming diets prefer not to emphasize this displeasing but basic fact.
When energy intake equals energy needs, our bodies are in 'energy balance'. This means that if you are fully grown, or are growing normally, and your weight is within certain limits (those that conform to longest life expectancy and least illness), you have achieved energy balance. You achieve it by balancing, on the one hand, your total energy intake, and, on the other, your level of activity. The more active you are, the more energy you need.
People differ in the efficiency of their energy expenditure. This may be due to differences in efficiency of movement, or because some people are not as efficient as others in burning up their 'fuel' supplies (that is, their 'metabolic efficiency' is lower). Thus, one person may eat much more than another, with equivalent levels of activity, and yet remain similar in weight. The more 'energy-efficient' person needs to be more careful about eating too much to avoid becoming overweight. However, the same person would survive better if food supplies were short.
Energy is also used, with varying efficiency, to maintain body temperature, to store fuels after a meal and to form bodily wastes. So even when you are not being active your body needs energy for vital processes. This minimum level of energy expenditure is known as the 'basal metabolic rate'. It is what keeps you alive even if you are completely at rest, fasting and at a comfortable temperature.
Body Weight
When our bodies are not in energy balance, excess energy is stored as fat (in adipose tissues). Women normally have more body fat than men, and this should be taken into account when considering whether to conform to the fashion to be very slim.
If you are on a weight-reduction programme, remember that body water is the main constituent lost during the first few days. It is only after 2 to 3 weeks of dieting that the loss is mainly fat. Remember also that not all people expend energy with the same efficiency.
APPETITE CAN CONTROL HOW MUCH ENERGY (FOOD) WE CONSUME
Appetite has an important role in controlling energy intake. When we are physically active, appetite is more correctly related to energy need than when we are inactive. At low levels of physical activity, we are more likely to feel hungry and to eat more than we need.
Also, a diet that is low in fat and high in carbohydrate and dietary fibre seems to allow appetite to be more correctly attuned to energy need. Because fatty foods are so palatable, more of them tend to be eaten than our bodies really need. They are also more energy dense than high-carbohydrate, high-dietary fibre foods.
Emotional Balance
Emotional wellness is the ability to successfully handle life’s stresses and adapt to change and difficult times. It involves being in tune with our emotions, understanding how to express them in a constructive manner, and knowing when to seek support when needed. Emotional wellness is characterized by self-care, stress reduction, relaxation, and the development of inner strength. It’s about being attentive to both positive and negative feelings, and having the tools to manage and understand those emotions. It also includes fostering a strong sense of empathy and compassion for oneself and others.