You have been good all week. You got to the gym every day and you even managed to abstain from the cookies that winked at you every day in the staff room at work as you got your salad out of the fridge. You weigh yourself on the Friday and so far so good, your weight loss efforts are on track (this story is going somewhere I promise). The weekend is here and Friday night calls for pizza, in bed, in your pajamas (hey we’ve all been there). One meal, no big deal right? You hop on the scales on Saturday and bam- you have put on 3kg.
THREE KILOGRAMS OVERNIGHT… is that even legal?!
Here’s what can often cause fluctuations in weight:
Changes in glycogen stores
To put it simply, your body stores energy as fat and glycogen. When you eat carbohydrates in particular, they are broken down into glucose and stored in the muscles and liver as glycogen. The interesting thing about glycogen is that it requires water in order to be stored. Thereby the difference in water weight between a glycogen depleted and replenished state can be quite significant. Kreitzman and colleagues found that glycogen is stored with three to four parts water, thereby glycogen loses or gains could potentially contribute to as much as a 5-kilogram weight change (1). So therefore that pizza you ate, in bed, in your pajamas- along side that sneaky bag of malteasers you had in the cupboard (still not judging) have done a stellar job of replenishing those glycogen stores.
Water retention from sodium
The body has a wonderful way of ensuring that we stay perfectly in balance (also known as homeostasis). When we eat a salty meal (insert Friday night pizza), the balance between sodium and water in the body fluid gets altered. This senses to the body that we need to take on more fluid to balance this back out so there is a decrease in urine excretion via the hormone aldosterone (2). Thereby more water on board resulting in an increase in body weight.
More so unrelated to the pizza, but an important thing to note, women do tend to retain water during menstruation (3). Therefore even the best weight loss efforts can be derailed simply by your hormones. This is completely normal and is just unfortunately one of those things you just have to accept.
Every other little thing going on in your ‘too complex to completely understand’ body
Alcohol, caffeine, stress, certain supplements or illness are just a small number of the endless things that can have an effect on body weight. Sometimes you just have to accept that the scale is going to move from time to time- completely out of your control.
So, what can you do?
Scales can be a great measure of progress in the long term but if used excessively will do nothing but weigh your self-esteem. Weighing yourself fortnightly as a measure of progress will help to cancel out the stress of day-to-day variations. Also focusing on how you feel, how your clothes fit, and taking progress photos can be another great way of measuring your progress.
1. Kreitzman SN, Coxon AY, Szaz KF. Glycogen storage: illusions of easy weight loss, excessive weight regain, and distortions in estimates of body composition. Am J Clin Nutr. 1992;56(1 Suppl):292S-3S.
2. Bhave G, Neilson EG. Body Fluid Dynamics: Back to the Future. Journal of the American Society of Nephrology : JASN. 2011;22(12):2166-81.
3. White CP, Hitchcock CL, Vigna YM, Prior JC. Fluid Retention over the Menstrual Cycle: 1-Year Data from the Prospective Ovulation Cohort. Obstetrics and Gynecology International. 2011;2011:138451.