I am writing this post because today I am feeling really at loss. This is my 3rd week where I am counting calories (1700 a day) and doing workout (gym 4 times a week - 30 minutes cardio and 30 minute weight, plus yoga or tai chi once a week).

Well guess what! I haven't lost a single gram! I am so frustrated. This has not happenned to me before. I am seeing my clothes looking better on me, and my BF says I look more "compact", but still I don't know why I am not losing.

Why is this happening? Any words of knowledge will be welcome.

The scale is not always the best measure, particularly in the short term. Working out will often cause people to hold onto water weight. That's why it's a good idea to also use a tape measure and take photos.

If you're not losing weight, it's possible that you're underestimating your caloric intake. You might consider cycling your calories. Maybe have 1400 four times a week and 1700 calories twice a week.

However, I"ll bet that you're actually losing fat (as evidenced by your more compact appearance and loser clothing) but it's just not showing up on the scale.

Hang in there! You're actually doing well.

It's happened to me too. I worked out at a bootcamp 5 days a week for a year, and also walked or ran. I didn't lose anything. So now I'm doing zumba twice a week and dieting. The weight is coming off.
My guess is my body was overworked.
Your workout doesn't sound too strenuous but maybe cut out something and drink more water if possible.

If you just started exercising like this than this is perfectly normal.

1700 calories may be on the high side if you have a desk job and sit around most of the day to get you where you want. If you're more active during the day it's probably fine.

These are all great points. Calorie cycling is not needed but can certainly be helpful to keeping one on track.

I know first-hand how frustrating that can be. What types of foods are you eating? Have you considered lowering your carb/sugar intake? That's one option. Another option would be to lower your calorie intake a couple of times per week? Maybe do 1200 twice per week if you can manage it?

Another consideration would be Intermittent Fasting. It's what I've been doing since July 31st and have lost over 10 lbs in the process. It's been a great experience not only with my body changes but also with my psych...

Just a couple of thoughts. It may be that you're sensitive to something that you're not aware of. For example, if I drink alcohol (just a bit!) I gain or not lose at all because I retain water like crazy. I also get bloated and I am sensitive to milk...

Hope that helps a bit.