Weight
Think of a garden. If the garden looks beautiful, then it will have had just the right amount of soil, just the right amount of nutrients, just the right amount of water, just the right amount of sun, just the right amount of plants, to make it thrive. If the sun is too harsh, then the garden will die. If the quantity of rain is too little or too much, then the garden will die. If there are too many plants, then the garden will not be able to support them and the garden will die. If the garden is not cared for, and weeds are allowed to grow, then the garden will die.
So to create a beautiful garden, we do not think twice about lavishing all the care necessary, and making sure that that garden receives all that it needs, and what it needs in the right proportions, otherwise what's the point in having a garden at all. So, why do we have a body that we do not feed with exactly what it needs. Why would someone lavish much more care on a garden than they would on themselves? It does not make sense does it?
If you have a pet, do you under or overfeed it? No, of course you do not. It would be a cruel thing to do, wouldn't it? It's a strange world, when we treat plants and animals better than ourselves, and even stranger, if these plants or animals were left to nature, nature would find just enough for them to survive, not too much and not too little.
Imagine a balloon. You feed a balloon with air. You blow the air in until it reaches an optimum size. What happens if you feed it too much air? It gets bigger and bigger, and eventually pops. You could say it then has a heart attack, couldn't you? That's what would happen to you , too, wouldn't it?
The Department of Health says that a woman needs a daily calorie intake of roughly 2000 calories and a man nees 2500. Since most adults lead a sedentary lifestyle, these figures apply to adults with low activity levels, so if you are active then allow a little more.
The RDA or Recommended Daily Allowance figures suggest that we should have approximately 60% carbohydrates, 30% fat and 10% protein within our daily calorie allowance. There are also a number of essential vitamins and minerals that we also must have. I won't bore you with the figures relating to all these, but be mindful that many items sold in shops these days do refer to these vitamins and minerals, giving the contents as a percentage of your recommended daily allowance. There are certainly books that you can buy that give all these figures, and it certainly would be possible for you to calculate your total daily intake in relation to carbohydrates, fat, protein, vitamins and minerals and make sure that you eat exactly what you are meant to eat. Most people, of course, would not be inclined to do this, but just take in mind that this is possible, and you could make sure that you eat, just enough to maintain your body in perfect condition, and no more.
Obviously, In order to lose weight you need to eat less calories per day than your body needs. To lose 1lb a week you need to reduce your intake by 500 calories per day. To lose weight at 2lb a week, which is the recommended rate, you need to reduce your calorie intake by 1000 calories per day.