Well I just checked the website, and it appears to have 2,000kcal/day locked in as a standard, which happens to be far more reasonable. Provided your nutritional intake is sufficient, you will burn about 1,500kcal/day if you stay in bed for 24 hours. But if you're not consuming that much energy, your body will notice, and will go through several processes that all account towards increased storage of energy as fat and decreased release of fat as energy (ie your body gets fatter, and it becomes harder to lose weight).
I've studied nutrition for 18 months as part of my study to become a fitness specialist, and did another two years of it at high school. I've studied body composition management for normal people who just need to get into shape, through to people who have metabolic disorders that seem to be preventing them from getting into shape. And I'm telling you, as a general rule, you want to work around 2,500kcal/day. A person who wants to lose weight without suffering health consequences should then do quality fitness training throughout the week, burning 300-500kcal/day through exercise, resulting in that number dropping back down to about 2,000kcal/day.