Fat Loss or Fluid Loss?

I came across yet another “health food” product today that promoted a lie. The flyer in question was advertising a protein powder. It was actually quite a decent product. It didn’t contain any artificial crap, no added sugar and the nutritional profile was good. What really got my goat though was one of the testimonials the flyer contained:

“After 1 week… I have lost 2kg.”


How do I know this? Because it is impossible to lose 2kg of fat in one week. And this is why:

Let’s say this lady (let’s call her Jennifer, because that’s her name on the flyer) is atypical of the average Australian female who weighs 71kg, is 162cm tall, and either “Insufficiently active” or “Inactive". Jennifer will need somewhere in the realm of 1,800 and 2,100 calories (7,500-8,800kJ) to maintain her weight.

Now, bear with me. There are a lot of numbers. (I will stick to calories for simplification).

For Jennifer to lose 1kg in one week, she will need to eat approximately 7,700kcal under her energy requirements during the week*. Per day, this equates to 1,100kcal under her energy requirements. This is also know as STARVATION. And I’m happy to write a blog post as to why starvation is really really really bad for our bodies. Just let me know and I’ll type away.

Another reason Jennifer’s weight loss can be attributed to fluid is because she is probably eating less carbohydrates than normal. Let’s face the facts, when we go on a diet to lose weight, the fashionable fad to follow is usually low carb. When we significantly eat less carbohydrates, our body starts to break down stored carbohydrate (called glycogen) to use for energy. Glycogen is stored with water so when our body breaks it down, water is released and we excrete it. This is the weight loss people experience at the beginning of a low carbohydrate diet or week-long “juice cleanse” or “alkaline cleanse” (?What is that anyway?). As our body starts to use stored fat for energy, weight loss slows down and we become disheartened because the protein powder sounded so promising in the beginning (“2kg in one week”).

Phew. If you’ve made it to here, nice one! That was a lot of info.

So, what is the best way to lose weight then? The answer is to lose weight slowly. And I know we’d all prefer to be the Hare instead of the Turtle, but the Turtle did win the race, remember. 

Slow weight loss means sustainable weight loss. We want our weight loss to be longterm. We want to create sensible eating habits. We want to establish healthy relationships with ALL foods so we can live a long, healthy, and enjoyable life. Slow weight loss allows us to achieve these things. It allows us to learn about our bodies - our cravings, our emotional ties with food, our internal barriers to change. Products that promise quick weight loss do not take important aspects into consideration and so are just setting us up for disappointment.

There is certainly a place in Jennifer’s diet for a protein powder, however it should be snuggled nicely amongst plenty of fresh vegetables and fruit, lean meats, seafood, legumes, nuts, seeds, whole-grains, dairy (if she so desires) and enjoyable “sometimes” foods such as chocolate, birthday cake and wine. That diet sounds pretty sustainable to me!

Hannah Baker
Dietitian, GCP Fitness

Please take into consideration that the calculations I have used above are approximate. Every individual is unique and will respond differently to a decrease in energy intake. You will also note there is no mention of physical activity. I did this to keep the article as simple as possible. Most importantly, I strongly recommend that you seek professional dietetic advice before commencing any weight loss plan. Your body and mental state will thank you for it - I promise!

*The Math:
1kg = 1000g
Fat = 37kJ per gram
Human fat is approx. 87% lipid
1000x87% = 870
870x37 = 32,190kJ (7700kcal)
7700kcal/7 = 1100kcal

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