Creating A Daily Calorie Deficit
A safe and effective way to lose weight is to exercise regularly and create a daily energy deficit.
It is recommended that an ideal calorific deficit should be no more than 20% of your total daily calorific requirement.
If calorie reduction is greater than this, then the body’s metabolism will respond by slowing down, and more lean tissue will be lost.
Energy Intake vs. Expenditure:
In order to maintain weight, you must have a positive balance where energy expenditure exceeds intake.
If there is a negative balance where intake exceeds expenditure over a period of time, weight gain can occur. If energy intake is equal to expenditure an individual is said to be in a state of energy balance.
As well as Basal Metabolic Rate (BMR), there are 3 main contributors of energy expenditure:
1. Physical Activity: Energy expended depends on intensity of activity. This is a great way to expend calories and ensure there is a positive in balance in energy
2. Dietary induced thermogenesis (DIT): All foods have an energy requirement needed to break it down and digest various components to provide energy. The thermogenic effect of food accounts for 5-15% of daily expenditure. The three main macronutrients have different thermogenic requirements; Protein requires 25-30% of its own energy to be metabolised, Carbohydrate requires 8% and fat requires 3%.
3. Adaptive Thermic Response: this refers to the resting energy expenditure in response to the following stimuli which can all alter BMR;
a. Psychological Thermogenesis – anxiety/stress stimulating adrenaline = heat production
b. Cold induced Thermogenesis – low temp, shivering/involuntary muscle contractions
c. Isometric Thermogenesis – increased muscle tension without movement (sitting, lying)
d. Dynamic Thermogenesis – negative work/heat produced by stretched muscle
e. Drug induced Thermogenesis – caffeine/alcohol
1. BMR is a measure of energy output over a 24hr period taking into account differences during sleep and other variances.
2. BMR can differ due to a variety of factors i.e. bodyweight, age, fitness levels, activity levels, food consumption, gender, height, weight and overall body size.
3. BMR accounts for 60-70% of total energy expenditure in a person. A person who is more active due to daily routines can expend up to 60% as opposed to roughly 10% for a sedentary person. PA and exercise can be used as the main determinants of calorie intake.
4. Men have a higher BMR due to a greater lean mass.
5. BMR reduces by 1-2% per decade from 20-70 years – linked mainly to the decline in lean mass attributed to a reduction in physical activity. As you age you cannot eat the same quantities without inevitable fat gains. Subsequently, your metabolism slows. This highlights the importance of exercise, and the effects of age in determining BMR over time.