But if I do not follow a strict diet, how can I lose weight?
A fast weight loss will be followed by fatigue and constant tiredness. To think that you are following a dieat also means that you feelt that you give up something, which increases the temptation to eat unhealthy again.
What you need to do is change the way you think about your diet. You have to make choices that you can imagine living for the rest of your life. For example, if you can not imagine stopping eating sugar for the rest of your life, it will not work in the long run that you do not eat sugar for three months. When that time is over, the weight will naturally return when you start eating sugar again.
What you need to do instead is think about what you can do in the long run. You know that large amounts of sugar are useless, can you then imagine simply reducing the amount of sugar you eat? You may decide to never eat sweets on weekdays and only in small quantities on Saturdays or something similar.
You need to think about what problems you have with food that make you eat unhealthy.
Here I will give some common examples for you to understand how I think:
You comfort eats. Then you need to do something about the problem that makes you feel that you need comfort in food and when you need to comfort yourself come up with an alternative way that is healthier. Maybe drink a good cup of tea and read a good book when you feel down instead of eating ice cream?
You eat too large portions and get too many calories. How can you reduce the amount of calories in the portions? Replace some of the food with salad and greens.
Drink water before each meal so you feel less hungry. Increase the amount of protein in the food so you are more satiated by the food. Plan when you are going to eat and do not wait until you are very hungry before eating.
You fall for temptations too often. Be careful not to be tempted. Do not have unhealthy food at home, do not go to the café that has the tastiest cake, do not watch the baking show on tv..
Have useful alternatives such as fruit at home when you get the urge for something (or homemade protein ice cream ala Greg Doucette).
I buy fast food because it's easy. Cook for several days in a row so you can only heat up a portion when you are hungry.
I buy unhealthy food when I'm at the store. It is important not to shop when you are hungry, then you usually buy with your stomach instead of with your head.
Have a list of what to buy even before you enter the store and stick to that list.