I like the moniker that these diets get, because not only do they tend to crash your weight into the ground, you usually crash and burn when you go on them too. The sales arguments are tempting, “Lose 30 lbs in 30 days”, “Lose 10 lbs in 10 days”, and appeals our urge to fix problems fast. The truth about them is that they are inherently unsustainable and all work off the same principles. As regular readers will know, I track every morsel of food that goes in my mouth, my daily calorie expenditure and my weight every single day. I also do refeeds once in a while, and I’m familiar with the mechanisms that make you drop “5 lbs in 5 days” or the like.
The picture on the left is an excerpt from my January log, right after I came off a 2 week full diet break for Christmas. As you can see, the first of January I weighed in at 89,10 kg (196 lbs), and the morning on the 8th of January I weighed in at 86 kg (189 lbs), this was a loss of 3,1 kg (7 lbs) in 7 days. If I calculate this into calories, it would require a deficit of 24500 calories.
The reality of my 7 lbs in 7 days is simple. Prior to my diet break I weighed in at 84 kg (185 lbs) in a glycogen depleted state, with very little stomach contents, and dehydrated. During Christmas, much like most people do, I ate and drank a large amount of food, filling up my glycogen stores to the max (adding 400 – 600 g of sugar + 1500 – 2000 grams of water). On New Years eve, I had a large turkey dinner with a lot of sodium, a lot of beer, desserts and various other things, that made sure my body was stuffed with glycogen, my stomach contents were full, I was retaining water (from the sodium and alcohol). This pushed my weight up to a peak of 89 kg, when realistically my weight was closer to 87 kg (my 3 day average was 87,5 and 6 day average 86,6).
I didn’t actually eat a calorie surplus of almost 40.000 calories for those 14 days. Meaning an intake of 2500 (my average daily energy expenditure) +2800 per day, making my total calorie intake for 2 weeks an average of 5300 calories per day. I ate a surplus of about 14000 calories, meaning 1000 per day for those 2 weeks. The rest was water and stomach contents. So my massive 5 kg weight gain was 2 kilo (5 lbs) of actual weight, and the rest was just water and stomach contents.
This week was the same case. I decided to have a cheat meal or two during the weekend, where I consumed drastically more calories than I normally do, to the tune of eating 5000 calories on Friday and 3000 calories on Saturday. The first column here is my calories consumed, the second column is my weight. As you can see, i went from 4 days weighing in at a stable 80,2 kg (176,8 lbs) to 83 kg (183 lb) over night.
I do admit that Friday and Saturday had some binge-eating aspects to them. More specifically, I wasn’t planning on eating that full 450g (1 lb) of peanuts and I was planning on a couple of beers, not 8, and the fact that my mother had made cheesecake was completely unplanned. However, I made sure I tracked everything I ate during my cheat, even in an inebriated state. My Fitbit was also in it’s normal position around my left arm, as I used it to raise pint after pint.
This means I have very good data on the entire cheat including calories burned. The first column here are my calories burned from my FITBIT, the second my intake according to My Fitness Pal. Over the course of the weekend, I ate a surplus of 2266 calories on Friday, which was my only calorie surplus that weekend. This would mean a maximum weight gain if it’s all fat of 0,29 kg (0,64 lbs), not a big deal. The weight gain on the other hand, was 2.8 kg (6,17 lbs)
This means that 2,51 kg (5,5 lbs) are unexplained by the food, but they are easily explained by glycogen and carbohydrate. Since my normal diet is lower than 50g of carbs every day, my muscles and liver are completely out of sugar. An adult weighing 70 kg (154 lbs) can store, 100 – 120 grams of glycogen in their liver and roughly 400 grams in their muscles. This is a total of about 500 grams. Each gram is bound to 3 – 4 grams of water. The total weight of this is 1500 grams to 2000 grams of water plus 500 grams of glycogen, for a total of 2 – 2,5 kg (4,4 – 5,5 lbs) weight gain.
A crash diet works in the same way that my rapid weight loss does. When you drastically reduce your calorie intake, and your carbohydrate intake, your body depletes your glycogen stores and releases the water causing a rapid weight loss. When you start eating normally again, your glycogen stores refill and the water comes back. From this perspective on the 13th, I was at my glycogen depleted weight, the average of the 17th and 18th is my real weight.