Hi chocolate girl,
Thanks for getting in touch.
Well done on the weight loss, but it sounds like your regime has taken its toll!
Firstly, to answer your question it is very difficult to determine what your required daily calorie intake should be, as you have mentioned, age, gender and activity levels all play a role and your calorie intake will also change as your weight does. Therefore I wouldn't necessarily be focusing on calories as part of your weight loss regime.
You were told by who that 1300 calories was the required daily intake to lose 16Ib? Were you told this figure before or after you decided to join the gym? This is an important question as your daily calorie requirement will be higher if you do regular exercise.
If you are doing 90 minute workouts 4 times a week, you are likely to burning your way through a fair amount of calories, which is not leaving your body with much change from 1300 a day to run the rest of the things it needs to do. If you are burning through calories you may even end up with low blood sugars, which will make you feel ill and shaky, guaranteed. I am sure you have looked after patients with hypos.
Were you doing much exercise before you joined the gym? If not, it is not surprising that your body is tired, you ideally need to gradually increase activity levels.
The other question I have to ask is how quickly do you want to achieve the 16Ib weight loss? The rate at which you are going you'll have reached your goals within a month! Then what...? Are you wanting to continue this calorie intake and exercise regime longterm? I suspect that you don't.
Experiment with your calorie intake and monitor the effects on your weight and how you feel, this would be the best way to find out exactly how many calories YOUR body needs. Always ensure that you are eating healthily as part of a calorie controlled diet, making sure that you get all of your essential vitamins and minerals.
In summary, I would suggest that you slow down a little! What you want is a regime that is sustainable, something that you can stick to in order to maintain a healthy weight. By doing this you are likely to slow the rate at which you achieve your weight loss goals but you are less likely to see the weight go back on once you take your foot of the accelerator!
Good luck with achieving your goals without too many side-effects.
Dr James Thompson
www.askdocjames.com