Fat loss plateaus can happen and mostly likely will happen. The fat maybe falling off you for the first 4 weeks and then all of a sudden it just stops. People may quit at this stage but the key to longterm fat loss is to asses your current plan make a few small changes and carry on.
What can you change to keep your fat loss coming?
1. Eat less
You may think you're in a calorie deficit but the reality is you may not be. Track your calories by using myfitnesspal app and see if you're actually in a deficit. Also track everything, it can be the small things that add up such as oils, a little spoon of Nutella and a few biscuits. Be honest with yourself and stay consistent with it 7 days a week. Don't forget though cutting your calories way too low can also backfire. 2. Increase the intensity
Ask yourself if you're really pushing yourself in the gym. A great way of tracking this is wearable HR monitors. This way you can see if you're in your right zone for training. Some wearable devices will also track how many calories you've done in the session. Try going a little harder and burn more calories in the same time that your currently doing. If you're doing moderate cardio most days maybe add in some high intensity sessions (shorter but more intense). You could even increase your weights slightly in your resistance training if you're reaching your rep range targets.
3. Better food choices
200 calories of broccoli is very different to 200 calories of donuts. The broccoli is packed with a lot more nutrients and has many other healthy benefits. I would recommend reducing processed foods as much as possible and go for more natural options. You can lose weight eating lower quality foods as long as you're still in a deficit however when you start reducing your calories even more it makes sense to make every calories count and get nutrient-dense foods.
4. Train more
If you think 1 training session a week is going to shed the fat then think again. Get a program together and aim for 3 cardio sessions and 3 strength sessions to start with per week. This is another key to long term fat loss. Just focusing on nutrition alone may help with fat loss however adding in some strength training and cardio will increase muscle, improving your body composition, day to day activities, and can help keep the fat off forever.
5. Track your progress accurately
Tracking from the scales does not tell you that its just fat that you're losing. Some people drop their calories too low that they also lose muscle. The scales my not be moving but your body shape could be. I've seen people get disheartened with the scales however when you show them some progress photos its all smiles. I would recommend tracking your progress more accurately.
A few ways you can track:
Skin callipers
DEXA scan
Progress photos
In body scan
The bod pod