Don't always trust the scale

A fluctuation in barometric pressure can wreak havoc on the scale. It's important to realize that the fluid fluctuations in our body can change by 2-4 pounds every single day.
Drs. Volek & Phinney, in their book The Art and Science of Low Carbohydrate Living, discuss why these ups and downs occur: "Humans are about 2/3 water; we each contain about 40 litres of water, and each litre weighs a bit over 2 pounds. Bodies effectively regulate fluid balance, but this is done within a 2-litre range. Within this range, the body doesn't really care if it is up to a litre below or above its ideal fluid level. Therefore, we all live within a 4-pound-wide grey zone that fluctuates daily. For people who weigh themselves frequently, this can be maddening.”
If you notice the scale jump for no apparent reason, DON'T PANIC. Instead, look at your average weight over a 7-to-14-day period. Many factors affect fluid changes: lack of sleep, chronic stress, barometric pressure, salty foods, inflamed muscles, extra sugar/starch, etc. Can you attribute the "gain” to any of those reasons? If you see the scale jump, usually it can be alleviated by increasing your water intake for a few days. Focus on your clothes and how your body is feeling physically.