I recommend going to the gym very often. And rely on a personal trainer. However, remembering that: 1) the personal trainer is not a dietician and cannot prescribe diets (at most give you some advice); 2) if the personal trainer insists on giving you a diet, change the gym immediately.
A long time ago, I joined two different gyms within a year. I wanted to lose weight a size that I had taken and that I did not know how to dispose of. When I signed up, I was both asked why I wanted to start a training program. The answer, the same in both cases, was: I would like to lose three kilos. I said it with Bridget Jones’ awkward and guilty expression.

And in both cases, in addition to the training program, I was offered a weight loss diet, which I foolishly agreed to follow. I was not given any dietary advice, beware. Anyone can give you those. I was prescribed a diet complete with sheets, days of the week, calories, foods. I didn’t ask for it but according to both people I was obliged to do it.
It wasn’t a tailor-made diet.

Personal trainer number one was a skeletal woman: she told me to drink a lot of water and prescribed me a starvation diet. Breakfast with a low-fat yogurt and a spoonful of cereal. No bread, no pasta, no sweets, no seasonings. At lunch a plate of vegetables, at dinner one hundred grams of fish or meat with vegetables, in the afternoon a fruit chosen from among the least sugary. In short, a starvation diet, with one day off, Sunday. Plus the gym. Doing a quick calculation of the caloric intake he had inflicted on me, I don’t think I exceeded six or seven hundred calories a day. I ran out quickly, lost little weight and when, after about ten days, I went back to eating normally, I also took something more, due to training. She, the personal trainer, scolded me sayingthat I didn’t have enough motivation . When I once heard her say in the morning that “even that yogurt seems too much to me, I can’t eat it, but how can you say you’re still hungry?”, I immediately understood that I was dealing with a crazy woman, weighing forty-seven All kilos of muscle, yes, but most of all she was crazy.

The second personal trainer was a beast.  He had given me a 1,700-calorie diet (more than double the first), because it was the same diet he had lost thirty pounds on. Too bad it was a giant of one meter and ninety. But it had worked with him, so he prescribed it to everyone: men and women, highs and lows, active and sedentary. All the same diet. Not a tailor -made diet . I tried it for four days, it was really too much. Meat every day, pasta for lunch first and roast slice for second. Protein dinner. I didn’t like meat for lunch, after pasta.

Here too: wonder why you couldn’t lose weight, weighed every day with those electronic scales that also calculate your fat mass index. A different fat mass value every day. He who believed that I was cheating, eating sweets between meals. A humiliation.
Moral of the story: I went to a dietician, he prescribed a tailor-made diet after evaluating my age, weight, body mass index and my basal metabolic rate, and I dropped the famous three kilos. The story has another moral: you don’t have to believe anyone who has managed to lose weight, thinking, like the philosopher in the second case, that if it went well for everyone, it will work for you too.. There is a science of nutrition, and people who improvise and shoot random diets can only make your situation worse. It doesn’t matter who he is, whether he is the guru, the stylist, the coach, the personal trainer.
For everyone, the question you have to ask is only one: sorry, but are you a dietician or a nutritionist?