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NUTRITION
We eat food to fuel our bodies for energy, growth and repair. Carbohydrates, proteins and fats are broken down by the digestive system into their simplest components: simple sugars, amino acids and fatty acids. Carbohydrates are the body's preferred fuel, although proteins and fats can be converted into energy too. This food energy is measured in calories (1 calorie = 4.2 kilojoules). This unit of measurement tells how much energy a food contains and how many calories are burned up during a particular exercise.
Fats and alcohol are by far the most energy dense foods. This is why they should only be consumed in moderation. The energy value per gram of various food components includes:
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Fat - 9 calories or 37 kilojoules (kJ) |
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Alcohol - 7 calories or 29 kJ |
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Carbohydrates - 4 calories or 16 kJ |
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Protein - 4 calories or 17 kJ |
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Water - 0 calories |
Too Many Calories
When we regularly eat more energy than our body needs, the excess is stored inside the fat cells. Just 1kg of body fat contains the equivalent of 9,000 calories. To lose 1kg of body fat in a week, you would need to burn an additional 9,000 calories, or around 1,800 calories a day. The best way to lose excess weight is to switch to a high fibre, low fat diet and, most importantly, to exercise regularly. Exercise helps to stimulate muscle development and increase metabolism.
Crash Diets
Most people who need to lose weight try dieting, which is a short term solution that only increases your body fat levels in the long run. The body responds to periods of deprivation or semi-starvation by lowering the metabolism. When dieting ceases and normal eating is resumed, the body burns even fewer calories than before because the metabolism is less efficient. Also, most of the weight lost during a crash diet is water and muscle tissue, not body fat. We need muscle tissue to burn kilojoules. Every time you crash diet, you lose a percentage of muscle tissue, which means your body can't burn as many calories as it could before dieting.
Fad Diets
We all want a way to lose weight fast. And there's no shortage of supposed solutions and it's hard to open a magazine without reading about the next miracle cure. Typically a fad diet shares some or all of the following characteristics:
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promises a quick fix |
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promotes 'magic' foods or combinations of foods |
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implies that food can change body chemistry |
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excludes or severely restricts food groups or nutrients, such as carbohydrates |
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has rigid rules that focus only on weight loss |
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makes claims based on a single study or testimonials only. |
By cutting out key foods, fad diets have been known to cause the following symptoms:
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dehydration |
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weakness and fatigue |
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nausea and headaches |
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constipation |
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inadequate vitamin and mineral intake. |
Fad diets that severely restrict food groups or nutrients may also be omitting the protective health effects that a balanced eating plan provides. It is not known whether fad diets are safe over the long term and whether they lead to an increased risk of various diseases.
Healthy Eating Guidelines
| 1. |
Limit your total fat intake. Fat should supply less than 30% of your total daily calories. Limit your intake of fat by having a semi-vegetarian diet. Choose lean meats, light-meat poultry without the skin, fish, and low-fat dairy products. In addition, cut back on vegetable oils and butter (or foods made with these) as well as on mayonnaise, salad dressings, and fried foods. |
| 2. |
Limit your intake of saturated fat to around 10% of your total daily calories. This is the kind of fat, found mostly in animal products, that boosts blood cholesterol levels and has other adverse health effects. It should supply less than one-third of the calories derived from fat. |
| 3. |
Keep your cholesterol intake below 300 milligrams per day. Cholesterol is found only in animal products, such as meats, poultry and dairy products. |
| 4. |
Eat foods rich in complex carbohydrates. Carbohydrates should contribute at least 40% of your total daily calories. To help meet this requirement, eat plenty of fruits and vegetables and six or more servings of grains (preferably whole grains) or legumes daily. This will help you obtain the 20 to 30 grams of dietary fibre you need each day, as well as provide important vitamins, minerals, and phytochemicals (plant chemicals essential for good health). |
| 5. |
Avoid too much sugar. Besides contributing to tooth decay, sugar is a source of "empty" calories and many foods that are high in sugar are also high in fat. |
| 6. |
Make sure to include green, orange, and yellow fruits and vegetables - such as broccoli, carrots, cantaloupe, and citrus fruits. The antioxidants and other nutrients in these foods are regarded as increasingly important in helping protect against developing certain types of cancer and other diseases. Eat five or more servings a day. |
| 7. |
Maintain a moderate protein intake. Protein should make up about 30% of your total daily calories. Choose low-fat sources. |
| 8. |
Eat a variety of foods. Don't try to fill your nutrient requirements by eating the same foods day in, day out. It is possible that not every essential nutrient has been identified, and so eating a wide assortment of foods helps to ensure that you will get all the necessary nutrients. In addition, this will limit your exposure to any pesticides or toxic substances that may be present in one particular food. |
| 9. |
Limit your sodium (salt) intake to no more than 2,400 milligrams (around one teaspoon of salt) per day. Cut back on your use of salt in cooking and on the table; avoid salty foods; check food labels for the inclusion of ingredients containing sodium. |
| 10. |
Maintain an adequate calcium intake. Calcium is essential for strong bones and teeth. Get your calcium from low fat sources, such as skim milk and low fat yogurt. |
| 11. |
Try to get your vitamins and minerals from foods, not from supplements. Supplements cannot substitute a healthy diet, which supplies nutrients and other compounds besides vitamins and minerals. Foods also provide the "synergy" that many nutrients require to be efficiently used in the body. |
| 12. |
Maintain a desirable weight. Balance energy (calorie) intake with energy output. Eating a low fat diet will help you maintain, or lower, your weight, as will regular exercise. |
| 13. |
If you drink alcohol, do so in moderation. A drink is defined as 355ml of beer, 120ml of wine, or 45ml of 80-proof spirits. Excess alcohol consumption leads to a variety of health problems. And alcoholic beverages can add many calories to your diet without supplying nutrients. Aim to have at least 3 alcohol-free days each week. |
Nothing contained on this information sheet is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.
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