okay, completely disregarding my feelings about the "adonis principles" here...
tweeter, you lost a very negligible amount of weight, i was thinking five pounds at the most, and i would have chalked up the difference in appearance to the lighting. when you shift from a dim light to a severe shadowing-overhead light and the difference is hardly noticeable, that means your in trouble.
since you lost 18 pounds apparently, that means you absolutely didn't lose 18 pounds of fat. 18 pounds of fat lost is a fair amount, if you were 200 pounds in the first picture, 18 pounds of fat is a full 9% of your bodyweight. unfortunately, you didn't just lose fat, you simply got smaller. 50g of protein in a caloric deficit is just stupid if you plan on holding onto muscle tissue.
one of the problems with the "adonis principles" is that it just assumes all weight lost is fat and goes from there. you'll probably get lean eventually, but you'll be a beanpole and then Team Gimmick Account will swarm out saying "see? that's how much muscle he actually had! you fatasses don't realize it!!" when in reality you're losing a LOT of muscle.
i've seen a lot of guys lose fat and look bigger afterwards, take dave gulledge:

320 pounds

265
that's 55 pounds lost. that's what it looks like when you really strip just fat. he looks gigantic at 265 whereas at 320 or so he was huge, but his shoulders for example didn't have that roundness to them due to the fat over them.
keep that in mind. if you're looking smaller, something's not right.