Weight loss, No Thanks! Here’s Why

The photo above was taken of me a few months before I turned 53. I have a small frame and a young frame of mind.
The latter is, I think, because I am creative and curious and reflective; and I like to really try to understand and properly support others, by taking my time and using all the resources on hand; including extrapolating my own experiences and knowledge; and this willingness and desire to help keeps me young.
Well, while advertisements and suggestions and stories and experiences abound about losing weight because some people are over-weight; my story is the opposite.
I have to gain weight.
At the time of writing this, June 2019, I weigh 40 kilograms or 88 pounds.
There’s a measure called the BMI or Body Mass Index, of which in February 2016, my doctor told me that at 46 kg then, I was at the lower end of this index.
It should be used in tandem with measuring your waist.
The BMI compares your weight to your height, and is calculated by dividing your weight (in kilograms) by your height (in metres squared). There’s an online Australian calculator that you can use, to calculate your own BMI.

Of course this is an estimate, and the point is that when I’m 44 kg I feel comfortable with that, and when I’m over 46 kg I feel that’s too much weight for me personally.
However at 44 kg if I lose 2 or 3 kilograms, I then start to feel weak.
In March this year I wrote about my weight dropping to 40 kg after I had a challenging episode in hospital in January this year.
Well, over 3 months, between then and the end of May, I put the 4 kg back on and that was due to returning to my normal diet, which included cakes or biscuits every day, ice-cream 2 or 3 times a week and milk chocolate a few times a week, plus dairy products.
Also I was prone to eating cooked breakfasts on the weekends, which were grilled sausages or bacon with eggs (sometimes poached, mostly fried).
But at the start of June 2019 I decided to stop eating all of those, to lower my cholesterol; and the weight once again was shed.
At 44 kg this year I also measured my waist circumference, to find that it was 80 cm and the website above goes to a page showing that women above this size shows one is carrying too much body fat.
Well, with my dropping to 40 kg, my trousers and jeans are now loose!
So, my question is that without eating the aforementioned, and WITH my exercising 3 times a week on my stationary exercise bike and running around at work 3 days a week; is there something I should be eating or doing to put on a little weight ??
Work friends told me to eat pasta or pudding but I don’t want to if that clocks up the fat quotient.
Do I have to eat a steak every day to build up muscles? Or lift weights?
Last weekend while I was “racing around at home” (meaning getting up and walking around doing things) I felt like I was going to topple over several times.
This week at work I was standing at a work colleague’s desk, chatting to him about sports and after a few minutes, I felt a bit faint and had to place my hands on his desk to keep myself upright.
So, to sum up from a collective point of view, if we’re thinking about and looking at weight issues, let’s also think about the other side of the spectrum!
Some people need to watch their weight, in terms of not loosing too much.
Any positive and polite comments posted in response to my story will be published and replied to. Thank you.
Below is a link to a Medium Story that I published in March 2019 when my weight first dropped to 40 kilograms.
