Don’t expect drastic results.
The bottom line is that you want to be thinner, let’s focus on that. The only way to accomplish this is by being in a caloric deficit. You should first estimate your TDEE with an online calculator, and second, subtract 10-20% of that from the total for the amount you should be eating to lose weight at a healthy rate. What is a healthy rate? Losing 0.5-1% of your total bodyweight each week is healthy in that it’s safe for lean mass retention and hormonal balance. Low carb and/or low fat diets are often problematic in that they are hard to maintain long term, they also don’t produce any additional weight loss, so I would recommend to avoid those.
Moving on from your nutrition, let’s consider your activities. Activities consume calories (something that is factored in when calculating TDEE), and as such increase the potential for being in a caloric deficit. Activities also have the potential to stimulate the growth of muscle tissue which is more metabolically active (burns more calories by its mere existence) than fatty tissue does. The best kind of activity for fat loss (not to be confused with weight loss) is therefore strength training, by which muscle mass is added to the body. The process of building muscle requires extra calories in and of itself, but a strength training session is also similar to a cardio training session in how many calories are consumed during the activity. This isn’t to say that you should only do strength training and you should avoid cardio, since both are beneficial and in different ways, it’s simply to highlight the value of strength training.
So now that you have nutrition and strength training down, that’s all you need right? Wrong. You’d be missing a critical component if that’s all you did. Rest and recovery are vital to this whole process. It’s why you can’t stay at the gym for hours on end and expect results. Your body’s capacity to grow and recover is limited, so you have to make sure to respect that. Get adequate sleep every night, don’t over train, and eat properly so that your body can recover properly.
What can you expect? If you are currently 85 kg, then the following is very much possible if you are doing everything right. By the end of week six, you could be 82.5-80kg.
Bonus, here is a useful little infographic you can refer to...