You just came back from your lovely summer holiday and you decided to stand on the scales (because obviously it was going to be kind to you after a holiday), only to nearly have a heart attack at the number it showed you.
“How could it be? I enjoyed myself, but I didn’t enjoy myself THAT much!”
What you’re seeing is very often not a true reflection of the changes in your body fat. You see, you have two main types of mass in your body; fat and lean mass.
Fat mass is exactly that – fat. Lean mass, on the other hand, is everything else (water, muscle, bone, organ tissue, etc.). When you stand on the scales, you’re only seeing how much MASS you have in total – not how much FAT mass you have. Regular weighing scales can’t decipher between lean and fat mass. When we see an increase in the scales, we tend to automatically think it must be entirely fat mass, however, more often than not, large and sudden changes in body weight are almost entirely lean body mass; in particular, water weight.
Our bodies regulate how much water we store within a pretty narrow range, but certain factors can still result in a decent amount of water being held and lost, which can result in large fluctuations in how much we weigh. It is very common for our bodies to retain a lot of water for a short period after a holiday for four main reasons:
1. Sodium
2. Flying
3. Changes in climate
4. Dehydration
## 1. Sodium
Sodium is an electrolyte better known as salt. The balance of sodium to other electrolytes (in particular, potassium), is very important for body fluid regulation (the amount of water we store in our body’s cells). A small change in the balance of sodium and potassium in our bodies can result in a significant change in fluid balance and result in either a loss or increase in water. When sodium is consumed, the kidneys bind water to sodium to help excrete it from the body. When sodium intake is abruptly increased. thirst increases and more fluid can be consumed, but urine output often does not change immediately, causing acute water retention to occur (1). In fact, Towson University showed that as little as an extra 400 mg of extra sodium in our diet can result in as much as 2 lb of water being gained (2)! Commercially prepared meals are typically high in sodium, which makes being on holiday very easy to suddenly increase your sodium intake and cause a temporary increase in body weight from water retention.
## 2. Flying
Long flights result in long periods of sitting and exposure to high altitudes. Both of these can result in water retention occurring. Due to the nature of prolonged sitting and inactivity, it is extremely common for fluid to build in the legs, known as edema, due to poor circulation of blood (3). High altitude can also result in the release of catecholamines and aldosterone, which can reduce blood flow to the renal system and cause fluid retention (4).
## 3. Change of climate
Going from cold to hot weather can result in heat acclimation, causing the plasma in your blood to expand temporarily. This expansion is your body’s way of improving cardiac function and protecting it from dehydration and overheating. However, it also causes more water to be retained by the body for a short period (5).
## 4. Dehydration
Last but certainly not least, dehydration is common during a holiday, especially a summer holiday, which too can result in water retention. Many factors can result in dehydration; the most common on holidays are:
- Not consuming enough fluid,
- Alcohol consumption, and
- Sweating.
You might be thinking “But wait, doesn’t dehydration mean the body loses water?” You’re right! But when dehydrated, the body reduces urine output to prevent further losses of water. When you start to consume more fluid and hydrate, urine output doesn’t match fluid intake for a while and the body can end up retaining more water than before (6).
## What to do
The best thing to do? Relax! Remain hydrated and resume your regular diet when you return home. All of these factors that cause water retention are temporary. Your body should regulate its fluid balance within a week of returning home. However, if the symptoms persist for longer than a week or get worse, then visit your doctor.
References
1. Relationship between Sodium Intake and Water Intake: The False and the True. Bankir, L., et al. 70(suppl 1), s.l. : Ann Nutr Metab, 2017, Vol. 17.
2. LiveStrong. How to Gain Water Weight. LiveStrong. [Online] [Cited: June 15, 2023.] https://www.livestrong.com/article/108760-gain-water-weight/.
3. Graduated compression stockings as a prophylactic measure in venous thromboembolism and edema of lower limbs triggered by air travel: a systematic review of clinical trials. Silva, L., et al. s.l. : Jornal Vascular Brasileiro, 2020. ISSN 1677-7301 (online).
4. Inder, S and Chandrashekhar, Y. Fluid Metabolism at High Altitudes. [book auth.] BM Marriott and SJ Carlson. Nutritional Needs In Cold And In High-Altitude Environments: Applications for Military Personnel in Field Operations. Washington : Institute of Medicine (US) Committee on Military Nutrition Research, 1996.
5. Cardiovascular adaptations supporting human exercise-heat acclimation. Periard, J., et al. s.l. : Autonomic Neuroscience, 2016, Vol. 196.6. The Acute Effects of Fluid Intake on Urine Specific Gravity and Fluid Retention in a Mildly Dehydrated State. Logan-Sprenger, H. and Spriet, L. 4, s.l. : Journal of Strength and Conditioning Research, 2013, Vol. 27.
