Frustrated!

This AIN'T the biggest loser and expecting to lose 10lbs in 2 weeks or so is not to be expected. The body is very very good at storage and keeping calories. It doesn't like to give up calories (just the survival set up in our bodies due to only small amounts of food since our caveman days).
You just have to be consistent day in and day out and take what your body gives you. Just like instruction, pupils don't learn everything about math, english, science, etc. in a month. It's continually progressing little by little to get to the big finish.

A.C.E. Certified Personal and Group Fitness Trainer
IDEA Fitness member
Kickboxing Certified Instructor
Been in fitness for 40 years and have studied kinesiology and nutrition

Seven pounds in 3 weeks is quite fast. I don't know your current weight, but someone well over 200 pounds can probably safely lose 2 pounds a week for a while, and still keep normal energy and strength.

Fast loss can be a trap: Hard to stick with long enough to lose a meaningful total amount of weight, increases health risks, increases potential for fatigue to bleed movement (so calorie expenditure) out of everyday life in subtle but meaningful ways.

Shows like Biggest Loser, tabloid headlines, and the blogosphere all feed those myths about losing 20 pounds in a month (or whatever). Let's look at that kind of claim, just as an example.

To lose 20 pounds in a month, a person would have to eat 2500 fewer calories daily on average than the number of calories they burn, or burn that many more calories than they eat by adding more activity (exercise or any other kind of movement).

The average woman's maintenance calories are around 2500 calories daily (USA data). Therefore, the average woman would need to eat zero, OR add a multi-mile daily run while holding food constant, OR a combination, to lose 20 pounds in a month. (For a 200-pound woman, it would be roughly 3.4 hours of running at 5 mph to burn 2500 calories. The exercise needn't be running, but that's a fairly time-efficient calorie burner to use as an example.)

The arithmetic of super fast loss just doesn't work.

To lose two pounds a week, it takes eating 1000 fewer calories daily (or moving that much more, or a combination). If we use that statistically average woman again, she'd need to eat about 1500 calories daily (2500-1000) or (at 200 pounds) add about an 80 minute daily run at 5mph, or some combination.

Those numbers are true whether the person is counting the calories, or using some other diet/exercise method. (Calorie counting just makes the numbers explicit; it isn't magically or universally a better or worse method than others.)

That 2 pounds a week arithmetic is hard enough, but it starts to come within the range of possible . . . though honestly, it'd probably be hard to stick with consistently for the 6 months plus that it would take to lose a total of about 50 pounds. On top of that, as a person gets lighter, calorie needs decrease, so it's actually going to require eating less (or moving even more), later in the process, to keep losing at the same fast (2 pounds a week) pace.

Slow but steady loss can therefore possibly get a person to goal weight in less calendar time than theoretically fast loss that involves deprivation-triggered over-eating, breaks in the action, or even giving up altogether because it's just too hard.

As a bonus, slower loss can give a person time to experiment and learn sustainable new habits that not only get them to goal weight, but help them stay there long term without relying on white-knuckled willpower every single second. (Many people find maintenance harder than loss, and around 80%+ of people who lose weight regain.)

I'm not trying to be discouraging. The effort to reach a healthy weight is IME very, very worthwhile.

I'm trying to be real. I was overweight to obese for around 30 years, took around a year to get to a healthy weight by calorie counting, and have been in a healthy range for around 8 years since. (That happened while I was in menopause, 59+ y/o, and severely hypothyroid (medicated), if that matters as context.)

For me, the subjective quality of life improvement has been HUGE, and that's without even getting into the health benefits of solidly normal blood pressure, cholesterol, etc. I want that for everyone, and most particularly here, I want that for YOU.

You are making fast progress. If you find that sustainable long-term, if it helps you develop new habits, then you're doing fine. If you reach a point where slower loss would be more realistic, slow the bus down.

You can do this. Keep at it. Only giving up fails.

I'm cheering for you!