ENERGY DEFICIT TO CREATE FAT LOSS.
A common and effective approach to reducing body fat is to establish a negative energy balance (less calories and /or more exercise).
A priority for an effective weight management programme is to lose body fat, whilst retaining as much lean mass as possible thereby minimising the fall in metabolic rate. The American College of Sports Medicine have suggested that to achieve this, a weight loss of 1 lb per week (from body fat) is recommended.
- Body weight reduction can be achieved through different strategies:
- Diet restriction – reduce dietary intake by 500 kcal per day.
- Exercise – Increase exercise/activity by 500 kcal per day.
- Exercise and dietary restriction combined – increase exercise/activity by 250 kcal and reduce dietary intake by 250 kcal per day.
Out of the above, a combination of exercise and dietary restriction, has been shown to stimulate fat loss whilst minimising the loss of lean mass and fall in metabolic rate.
Research indicates that if the energy deficit is too great then body fat is more likely to return, possibly to an even greater level.
Eating little and often is proven to be the best way of approaching weight loss whilst minimising the loss of lean mass and subsequent fall in metabolism. A minimum of three meals a day is advised.
Whilst we all share many similarities, we are each an individual in our own right, shaped by our genetic make-up and environment. In dietary terms, what suits one person may not suit another. Trying to determine what foods will work for any given individual may require time, skill and a little trial and error.
‘One man’s food is another man’s poison’ or woman in this instance (Lucretius, 200 BC).
The goal of weight management is to prevent the accumulation of excess body fat and for those who are already overweight, to reduce body fat to an acceptably safe level in order to prevent the health risks associated with obesity.
There are several different methods commonly used and established for assessing body composition and determining health risks associated with both weight and body shape.
- Body Mass Index (BMI).
- Abdominal Circumference.
Whilst each of these methods do not specifically measure body fat they are simple and have clearly shown valid markers for associated health risks.
BMI – The table below provides information on how to assess health risk.
|Obesity class||BMI (kg/m2)|
|Normal Acceptable||18.5 – 24.9|
|Overweight Special Attention||25 – 29.9|
|Obesity Medical Referral||I||30 – 34.9|
|Servere Obesity||II||35 – 34.9|
Abdominal Circumference – The table below provides identification of the risks of morbidity.
|Lowered Risk||High Risk|
|Women < 80cm (<32 inches)||Women > 88cm (>35 inches)|
ENERGY AND METABOLISM.
A person’s energy and metabolism will be personal. To gain a more accurate calculation of energy expenditure to determine a healthy calorie intake for you, the information below along with the formulas below will give you an estimated calorie intake.
Basal Metabolic Rate (BMR) – Your BMR is the number of calories required to keep your body functioning at rest, also known as your metabolism.
- BMR for Women = 655 + (9.6 * weight [kg]) + (1.8 * size [cm]) − (4.7 * age [years]
Total Daily Energy Expenditure (TDEE) – This is the amount of calories you need to fuel all the functions, exercise and activity of the body. Knowing how to estimate the amount of calories we need per day can give us a starting point in starting a calorie controlled diet. Once you’ve calculated your BMR, this is then put into the Harris Benedict Formula, which calculates the total calorie intake required to maintain your current weight. This is as follows:
- Little/no exercise:BMR * 1.2 = Total Calorie Need
- Light exercise: BMR * 1.375 = Total Calorie Need
- Moderate exercise (3-5 days/wk): BMR * 1.55 = Total Calorie Need
- Very active (6-7 days/wk):BMR * 1.725 = Total Calorie Need
- Extra active (very active & physical job):BMR * 1.9 = Total Calorie Need
- 48 years old
- 5’ 8” tall (172cm)
- 13 stone (82.5kg)
BMR = 655 + 523 + 302 – 141 = 1531 calories per day at rest
TDDE = 1531 x 1.2 (little or no exercise) = 1837 calories per day to maintain current weight.
To create an energy deficit from the example above you would need to reduce your calorie intake of 1837 per day and/or increase your activity levels.