One Kilogram of Fat

We eat food to fuel our bodies for energy, growth and repair. However, when we regularly eat more energy than our body needs, the excess is stored inside fat cells. There are roughly 37,000 kilojoules (kJ) in one kilogram of fat.

To lose a kilogram of body fat in a week, you would need to cut back your food intake and/or work off 37,000 kJ, or around 5,000 kJ a day.

Physical Activity

Physical activity not only burns up stored energy but can also help increase muscle development (in particular resistance or weight training) and the more muscle tissue you have, the more kilojoules you can burn.

The amount of kilojoules you burn will depend on number of factors such as your age, sex, body type, exercise intensity and duration. The average man can burn around 1,100 kJ/hour walking and 3,000 kJ/hour running while the average woman can burn 825 kJ/hour walking and 2,250 kJ/hour running.

Food Intake

What you put in your mouth is in fact more important than the amount of physical activity you partake. As noted in our previous blog post, The 70-30 Rule, 70% of your fat loss effort should be spent on nutrition and 30% on exercise. For most people it’s the 70% that’s the hardest. If you eat a large serving of creamy pasta and wash it down with a couple glasses of wine after your run, you will actually be eating more kilojoules than you burned off.

The keys to healthy eating are to eat more vegetables and whole grains, watch the portion sizes, be careful of what you drink (especially alcohol) and everything in moderation.

Reasonable and healthy weight loss should be between 0.5 to 1.0 kg per week for most people. By increasing your level of physical activity and reducing your overall kilojoule intake, you will be able to lose those 37,000 kJ without much trouble. Stay focused, motivated and you should be able to shed that kilogram of body fat in no time.


Andrew is the owner and principal trainer of Health Jigsaw. He is a highly sought-after trainer and has been a personal trainer since 1997. Andrew has previously worked in a five-star luxury resort, large fitness centres and an exclusive personal training studio.

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