You might think you’re doing everything right, eating the right things, doing plenty of exercise yet you just can’t shift the weight. This post is going to demonstrate just how difficult it is to lose body fat. It’s a case study, it’ll take about 10 minutes to read, if maths doesn’t agree with you, skip to the last paragraph…
Body Fat %: 40
- 60mins resistance training
- 60mins swimming
- 60mins yoga
- 60mins weights and core class
Jess works in an office so she sits at the computer all day, she’s pretty inactive apart form her 4 exercise sessions each week (which is more than most).
Jess eats 1000 calories every day, she tracked her calorie intake for one month and didn’t lose even a single pound. The only thing she ate beyond the 1000 calories over the course of the whole month was 1 pizza and a tub of Ben & Jerrys as a treat.
The Maths Behind It All
To work out Jess’s basal metabolic rate (how many calories she burns daily just to survive) we used the ‘Cunningham equation’ (21.6 x Fat Free Mass) + 370. This works out that she needs 1277 calories per day to survive. Jess has been dieting for the past year, so when we factor in metabolic adaptions from dieting, we can estimate a reduction in 15%. So 1277 x 0.85= 1085kcal per day.
We then need to factor in her exercise (which burns calories). As Jess is generally inactive through the week, we multiply her BMR by 1.1 (this is her activity factor). So 1085 x 1.1 = 1194. Multiply this by 7 to give her weekly energy expenditure (before exercise) …. 8358kcal.
Weekly Exercise Energy Expenditure
- 1 x 60min Resistance Training (300kcal)
- 1 x 60min Swimming (350kcal)
- 1 x 60min Yoga (250kcal)
- 1 x 60min Weights and Core Class (250kcal)
Total calories burnt through exercise: 1150kcal
So total weekly energy expenditure….. 8358 + 1150 = 9508 kcal/week.
Jess eats 7000kcal per week, so… 9508 – 7000 = 2508kcal is her weekly calorie deficit. So her monthly deficit is 10032kcal.
How many kg is 2508kcal in regards to weight loss? 1kg of body fat contains 7700kcals. So 2508/7700 = 0.32kg (0.7lbs).
There’s approx. 1600kcal in a whole pizza.
There’s 1350kcals in a tub of Ben & Jerrys ice cream.
That’s an extra 2950kcal per month.
Jess’s ACTUAL MONTHLY DEFICIT = 10032 – 2950 = 7082calories.
7082/7700 = 0.92kg of fat loss. Consider she might gain 1kg of water weight due to her menstrual cycle, she has actually GAINED 0.8kg over the month.
To summarise…. Jess ate 1000 calories every day for a month, had a treat once in the whole month which was a pizza and a small tub of ice cream. She exercised 4 times a week every week. Mathematically, she GAINED nearly a kilogram. Weight loss isn’t always simple. Sometimes you need to be realistic about how long it takes to drop body fat. One pound or 0.5kg a week is a realistic target for most. To achieve this, you’d need to be in a deficit of 3500kcals over a week. Easier said than done! If you need help putting a plan in place to lose weight, fill in our inquiry form to book your free consultation today!
(credit to Mac Nutrition)