When you sync the first time, you have to make a decision whether to sync from website to app or from app to website. Maybe you chose the wrong option? If you have a freshly installed app with no info and then sync TO the website, it'll delete everything.
I have installed FS on my phone several times, and synced with no trouble. I do, however, make absolutely sure to pick the right option.
"Losing weight is never about eating as little as possible"
"You wouldn't worry so much about what others think of you if you realized how seldom they do.
― Eleanor Roosevelt
"Do. Or do not. There is no trying."
- Master Yoda.
From October 4th 2010 to April 3rd 2012 I lost half my body weight - 80 kilos/170 lbs. Since then, I have had two cosmetic surgeries to remove excess skin. I have now quadrupled my strength, gained several kilos in muscle mass, and today I focus on building muscle, optimizing my diet, and living healthy. I am stronger, healthier, thinner, happier!