In my Plymouth hypnotherapy practice I’ve researched several online tools for helping people to design healthy and realistic weight loss programmes for themselves.
This one calculates your “Body Mass Index” (BMI) which is the ratio of your weight to your height, and also your “Basal Metabolic Rate” (BMR).
Be aware though that BMI can be misleading- if you’re very muscular your BMI might appear excessive when you’re actually very fit. It’s only a rough guide- body fat measurements are better.
Let’s look at an example. Jane is 1.6 metres tall, weighs 70 kilos, and is 35 years old. (Metabolism slows down a bit with age). The calculator tells us that her BMI = 27.34, which probably means she’s overweight and at increased risk of serious illness.
So how can she best lose weight? If we turn to the BMR calculator on the same website, and put in the same figures, we find that Jane’s BMR is 1450 calories. That’s how much she would need to eat for her weight to stay the same, neither gaining nor losing, if she was laying in bed doing nothing all day.
But of course she won’t be lying in bed all day unless she’s seriously ill. We can use the “Harris Benedict Equation” on the same website to find Jane’s actual calorie needs. It’s just a number by which we multiply Jane’s BMR. Obviously the number varies according to how much exercise she gets. Let’s say she’s an office worker who takes little exercise. The chart says that her Harris Benedict number is 1.2. So 1450 x 1.2 = 1740 calories per day. This is how many calories she needs to eat to stay the same weight, neither gaining nor losing. To lose weight she has to eat less than 1740 calories per day.
Suppose Jane wants to lose 7 kilos- this would bring her down to 63 kg with a BMI of 24.61, just within the healthy range of BMI. It takes roughly 7000 calories to make one kilogram of fat. So over the course of time Jane needs to cut out a total of 7000 x 7 calories = 49,000 calories.
Most people want to lose weight as quickly as possible but I’ll explain later why that’s a very bad idea. Experts recommend that women don’t go below 1200 calories per day and men don’t go below 1500. If Jane cuts her daily intake by 500 calories, eating 1240 calories per day, she’ll keep within these safe limits.
So how long will she take to reach her target weight? 49,000 calories divided by 500 calories = 98 days. So Jane will take just over 3 months to get down to a healthy weight. If she prefers a less drastic reduction and only cuts by 250 calories daily, her weight loss will take twice as long, about 6 to 7 months.
Many people want to lose as rapidly as possible. This is because our brains can focus much easier on immediate rewards. However, this rapid weight loss requires much greater sacrifice- twice as much reduction in calories to lose weight in half the time. Many people are prepared to make that extreme sacrifice to gain quick results. But there’s a problem here too, because of how our bodies work.
Our bodies are designed to survive frequent food shortages. So when we cut our food intake severely, our body automatically goes into “famine survival mode,” adjusting to minimise energy expenditure. When we start eating normally again our body takes a while to “catch up” with us, and remains in “famine survival mode” for a while even though we’re eating normally. Result is that because less of the energy in our food is being burned to keep us going, more of it will be stored as fat.
This is why you so often hear of people losing huge amounts of weight through crash dieting, then putting all of it back on and more as soon as they return to normal eating. Because of this, and for other reasons, the slow and steady approach to losing weight is much better if you want to keep the weight off permanently.
The good news is firstly that even moderate exercise would make a big difference to Jane’s dietary needs. You can do the calculation again for different “Harris Benedict” numbers to see how much fewer calories she would need to cut out if she took more exercise.
Secondly, because modern factory-made “junk foods” contain so many calories, reducing intake by even 500 calories a day is not that difficult. This site contains a huge list of foods showing the amount of calories in normal portions of each food.
Click HERE for another free online weight loss resource and my latest post on “Weight Loss Hypnotherapy and Body Image”.