So, my height is 5'4" and I weigh around 83 kg which gives a pretty bad ratio of BMI. My Triglyceride level is 238 mg/dl (desirable amount should be <160), HDL Cholesterol is 31 mg/dl (borderline limit is 35-60), LDL Cholesterol is 89 mg/dl (Desirable limit should be <130). My TSH level is borderline, which is, 6.72 μIU/ml (Among adults, it should be 0.27 - 4.2). My cardiologist recommended me a 1400 Calorie low-fat diet.
I don't know for sure if my metabolism is slow (naturally), but it is a fact that I have been obese since childhood. In 2016, I lost 12 kg of weight through diet and exercise. However, because of some circumstances, I had to quit exercising for over a year (almost). I gained whatever I lost through diet and exercise. So, I went to a dietician. She gave me a chart and she said that I should not join any gym and should rather walk for 1 hour, everyday. I asked her that why is joining a gym and exercising there a problem? She said, that people who unjoin a gym for whatever reasons, later, end up adding weight (fat).
Is it true? And if so, is it because of their slow metabolism rate or is it because they don't trim down their diet after unjoining a gym? I could not find any evidence for her claims, so any help in this regard will be helpful.
P.S. When I used to work our earlier, I used to do 30 minutes of cardio followed by 1 hour of strength (resistance) training.