I have been under BMI 25 for most of my life, but was up at 26 when diagnosed with Type 2.
Was already dong low fat (high brown carbs) for over 10yrs by then, with nothing to show for it but steadily gaining a little more weight each year and getting a 3x bypass op , then T2 Diabetes.
I rejected advice to double down on low fat after reading the posts on this forum.
I got a BG monitor (in my case a Tee2 which has relatively cheap test strips), tested before and 2hrs after every meal until I knew the effect on me of the different foods I usually ate.
Ended up going low car - as low as 20gms to 40gms per day. Didn't try to lose weight, didn't count calories, didn't do more exercise. I lost weigh anyway!
I knew to supplement with extra Potassium, magnesium, as well as eat more salt, so didn't suffer from Keto 'flu, I didn't suffer from hunger either, at first I was probably eating more calories per day that before going Low Carb due to going back to going back to full fat dairy and eating the fat on bacon, lamb etc. that came naturally with that cut of meat.
Blood Glucose, HbA1C, Blood pressure, Triglycerides and weight all came down - so all good!
HDL and LDL both went up, was concerned about the LDL at first, but studied the literature and discovered that ratios matter more then totals and my ratios had all improved suggesting that the quality of my LDL had improved (and in any case LDL is a requirement for life - immune system, hormones etc.)