Phentermine
The rule is simply stated but requires will power to apply. To lose weight, you have to burn more calories than you eat (a reasonable target is to burn 500 calories less than you need per day). The technical term for this kind of diet is hypocaloric or net-loss calorie diet. This kind of diet can come as a shock to your body. To help you keep to it, your physician will often prescribe phentermine to reduce your appetite and make you feel less hungry.
To help you understand why this approach to weight loss works, you burn calories when you are at rest. Burning calories pumps blood round your body, lets you breathe, and so on. More calories burn when you start to move around. So when you assess your daily routines, this would give you an idea of the total number of calories per day you require for steady state. To lose one pound, you have to burn about 3500 calories more than your steady state number.
How do you work out what to eat?
1. The first step is to calculate your basal metabolic rate (BMR). The full scientific test requires a gas analysis through calorimetry. A rough estimate can be made by using age, sex, height and weight. One set of equations is the following:
For women: BMR = 655 + (height in inches x 4.7) + (weight in pounds x 4.35) - (age in years x 4.7)
For men: BMR = 66 + (height in inches x 12.7) + (weight in pounds x 6.23) - (age in years x 6.8)
Thus, take a 47 year old woman 5ft 7ins tall and weighing 175lb.
BMR = 655 + (67 x 4.7) + (175 x 4.35) - (47 x 4.7) = 1510 kcal per day.
There are only BMR calculators for both metric and imperial values.
2. The second step is to calculate your activity level. This is where you have to be completely honest with yourself. It does not help you to "cheat" to get a better figure. You should divide your day into levels of activity. The first and most obvious possibility is that you are "resting", i.e. asleep or sitting down. Then we get into a rising scale:
• very light where you are active while sitting or standing, so you might be typing, sewing, knitting or driving, or cooking, ironing, etc.;
• light where you are walking at around 3 mph across level ground, cleaning the house, looking after your children, playing golf, working as an electrician, carpenter, mechanic, etc.;
• moderate where you are walking more rapidly or uphill, carrying a load over distance, digging or hoeing in the garden, playing tennis, cycling, working out with weights in the gym, etc.;
• heavy where you are carrying heavy loads, or playing sports requiring serious commitment like squash, football, etc.
This is very crude and depends on you estimating average time which may vary considerably from day-to-day. So you might have a very low level of activity during the week, but exercise significantly at the weekends. There are estimated calorie calculators online to guide you.
For those of you who prefer the science, the World Health Organisation produced the standardised physical activity levels (PAL).1 PAL is calculated as total daily energy expenditure (TDEE) over BMR (TDEE/BMR). Your activity-related energy expenditure (AEE) = (0.9 TDEE) - BMR. These calculations are considered insensitive because they do not allow for age variation and so cannot distinguish between children, young adults and baby boomers. In 1995, the whole issue of how to calculate energy requirements was reconsidered by the International Dietary Exchange Consultancy Group (IDECG).2 It concluded that energy expenditure data based on the doubly labelled water (DLW) method, heart rate monitoring and activity diaries was a better system. Over time, the DLW method has become the gold standard for measuring energy expenditure3.
3. The third step is to monitor how many calories you eat per day. This requires you to keep a food diary, recording what you eat and drink. Again, there are calorie counters online that will help you estimate your intake.
You are now in a position to make an overall assessment. Let us take our 47 year old woman and assume that she has an essentially sedentary lifestyle with no serious exercise of any kind. This would give her a BMR of 1510 + 350 = 1860 calories per day. Then let us assume that her diary shows that she consumes 2110 calories per day. This additional calorie intake represents a weight gain of about one pound every two weeks. But if she could reduce her intake by 500 calories per day, she would lose one pound every week even without exercise. Should she find herself hungry and this is making it difficult for her to eat the lower calorie portions, phentermine can help by suppressing the hunger signals.
The question, therefore, is what does 500 calories look like. There are many sites that list the calorie value of different kinds of food. You simply have to get into the routine of counting the calories, exercising a little more and taking phentermine as directed by your physician.
References:
1. World Health Organisation. Energy and Protein Requirements. Report of a Joint FAO/WHO/UNU Expert Consultation. WHO: Geneva; 1985.
2. Torun B, Davies PSW, Livingstone MBE, Paolissis M, Spurr GB. Energy requirements and dietary recommendations for children and adolescents 1 to 18 years old. Eur J Clin Nutr 1996; 50: S37–S81.
3. Westerterp KR, Bouten CVC. Physical activity assessment: comparison between movement registration and double labelled water method. Z Ernahrungswiss 1997; 36: 263–267.
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