Please, take 5 minutes of your free time to check my last draft, point out my mistakes and suggest useful solutions.
Thanks!
Essay topics: Childhood obesity is increasing at rapid rates in developed countries.
What are some of the causes of this problem? What are some ways in which childhood obesity rates can be reduced?
Obesity amongst children is a growing concern in developed nations, since they are witnessing an overwhelming increase in numbers of obese kids. The cheap price of processed food and the lack of physical exercise could be considered as main causes of this epidemic. Fortunately, local governments can easily tackle this social issue by imposing high taxes on unhealthy foods and making mandatory the practice of exercise.
Really well written introduction! Please keep following this in future. Good paraphrasing. Addressed both questions in essay in introduction and gave a glimpse of essay. Well done!
First,
it is a palpable fact that the price of unhealthy/processed food (those filled with sugar and
unnamable ingredients) is quite cheaper than healthy ones (vegetables, fruits, organic products).
I don't like these kind of arguments. It is already known, It is a fact, there is no doubt. Please don't write your arguments like this. State a fact and tell why is that a fact.
Families, particularly low-income, prefer to spend their food budget in this type of food, since a big amount of products can be bought with less money.
Not sure I agree but the way it is written is fine.
Secondly,
it is no a secret See again it is no secret ... you need to get rid of this.
that nowadays kids spends hours on end, either watching TV or playing video games. They barely do exercise, or even practice a sport, resulting in a sedentary lifestyle. These two factors, an unhealthy diet and a lack of exercise, highly contribute to the childhood obesity.
Other than the issues highlighted well written!
Luckily, there are feasible solutions to overcome this problem. Public administrations can enact legislation in which levy taxes on processed foods. This extra charge would definitely act as a deterrent for families who normally buy these items.
You see the issue here. You said in your above paragraph that poor families bought such kind of food. Now you made it expensive for them. But you didn't make the healthier food cheaper. So how is it a solution? How does it help them? You are penalizing them but not really helping them.
Additionally, by law, governments can declare the act of exercising as an intrinsic obligation for all kids, making directly liable parents, with economic fine, if kids don't practice a sport or exercise their bodies.
No they can't. It is a democracy. you can't make things mandatory by law just like that.
In Spain, for instance, who has the second high rate of childhood obesity in Europe, has been applied these remedies since 2016, and has reduced by 30% the obesity rate in kids, according to the last report.
I like the premise of arguments. But they have not been presented well. And I know people say oh IELTS is a language test and they don't look at the validity of their argument. I have never really understood how they will test "Task Response" then. In my opinion the second paragraph lacks task response but I may be wrong.
To sum up, the uncontrolled increase of obese children is due to the fact that many families feed theirs kids with the cheapest food on the market, and do not encourage them to do exercise, letting that TV being their best friend. However, governments hold the power to put a halt on this increasing problem by making high taxable unhealthy foodstuffs and legally obligating kids to exercise.
Ok well written conclusion in the context. I may not like your arguments but you did revisit your arguments in your conclusion.
Overall, I think this was well written from essay structure perspective. You followed all what is needed from an IELTS introduction and conclusion. And more or less have hit everything in Task response. I think you should be able to get a 7.5+ score on this one. 
