Because it's your first day and you're probs not used to eating that much volume per meal. Try to finish it after a small while and over time your body will adjust to get bigger meals in.
Welcome! Loving the tenacious handle - bodes very well!
Agree with Essie, plus maybe focus a bit more on calorie dense fruits and perhaps a little less fluid to start (not sure how much water you're adding to your smoothies - reducing this or simply eating straight-up dates/fruit might work better initially).
One thing I will say though, you might genuinely not need 1,000 cals for breakfast, so I would suggest that you don't keep forcing it if it really doesn't feel right. (Give it a good go first though, natch!) I've been eating this way for years, and eat about 3,000 cals a day, but my max cals for my trusty old breakfast smoothie are about 800, I genuinely can't fit in 1,000 cals, even if I exercise beforehand.
If this doesn't change within 30-45 days try splitting up your meals & have 6 small meals instead of 3 big.
You can't finish probably because you have maxed the digestive capacity of your stomach. And your body is screaming 'noooo more, we are at full capacity now'. This has to do with enzymes and all that stuff the body needs to add to the food to digest it, I believe.
What everyone else has said here is perfect. Just adjust your meals to be comfortable in size. In not too much time, your capacity will increase. But it is important to learn to go easy on our bodies, they are intelligent and provide us with lots of information about its needs and activities through those innocent, transparent signals.
And to ask questions here is also smart :)
Along with what the others have said another reason could be because your stomach is smaller from eating calorie dense meals for years on end which doesn't require the volume of space that the same calories from fruit or vegetables do.
I have found that I graze my way through the day. I eat and then an hour later I eat again and so on. My co-workers are kind of weirded out by how much I eat through the day but am visibly losing weight...I just ask them if they ever read Thinner and then laugh maniacally as I walk away.
Just eat when you're hungry and eat until you're full. Don't worry about calories
I don't agree, it's very easy in the beginning not to eat enough, and weight comes off very very fast (as well as your overall energy). She has to train her stomach, then once it will have expanded to the correct size, she won't have to worry as much about calories anymore.
Yeah, I am not so sure if this helps most people. Maybe some can do it like that. But they seem to be the exception.
Worrying isn't good of course. But paying attention and making sure we get enough calories, knowing we eat enough, that is smart.
It takes months to adapt, and it's worth it.
I make a hug pitcher of smoothie and it take me about two hours to drink. I have a small stomach because I was bulimic, so just stick it in a big jug and sip till it's gone.