Hello huynhtho for this essay. It's very useful for us here and I hope it helps many people!

First of all, it's 387 words long, which is far too long for IELTS. I recommend writing between 250 and 300 or maybe 320 words.  

Any more than 300 and you may be penalizing yourself due to rushed writing and increased errors. There is no penalty for writing more than 250, but you will be tired by the time it comes to Task 2 writing, and most candidates who write long essays score lower because of mistakes in grammar or layout.

You can check average sentence length, word count, and many other useful statistics by using one of the two readability links at the top of this page-  this one at read-able.com, or this one at online-utility.org.

Your average sentence length is 15.5, which is OK, but you should try to reduce it to below 15 words per sentence on average. Add more short sentences, and break up longer ones.

Rewrite

Instead of looking at individual sentences, I’ve done a quick rewrite of your essay. I've removed unnecessary sentences and padding. I've also removed huge chunks of unnecessary detail. But I've kept all your ideas and your organization.

Some people suggest that increasing the price of fattening foods will solve the problem of obesity. I agree in part, but obesity is such a big problem that increasing the price of some foods is only one of many steps we need to take.

Making high-fat foods more expensive may discourage some consumers from buying unhealthy food. Denmark was one of the first countries to introduce a tax on high fat food such as butter, potato chips and many processed foods. Hungary has adopted a similar policy with a tax on hamburgers.

However, increasing the price of some foods does not attack the root of the problem, and other approaches are needed. Governments can restrict the sale of fast foods and limit advertising, particularly on school campuses. Health education is a second strategy. People need to be aware of the dangers of an unhealthy diet. Parents also play an important role: they need to give their children nutritious food and encourage them to exercise.

In conclusion, if we want a healthier society, education, good eating habits and exercise are more important than higher prices on certain foods. Both governments and individuals have to act to solve this problem.

There are only 205 words in this rewrite. Now it’s too short! So where did your 387 words go? The problem is that the even though your second paragraph is an astonishing 178 words long, it doesn’t have many ideas. It has lots of information about Denmark’s new law, but not really many ideas for or against the idea of increasing the price of food.

Your third paragraph has three ideas (government restrictions, health education, parents) so that’s fine at 88 words. But we need much clearer topic sentences in paragraphs 2 and 3 so that it’s clear to readers and examiners what the topic of each paragraph is.

Have a look at the official descriptors for IELTS Task 2 Writing (public version) here, under Coherence and Cohesion, and see:

• Band 4: “may not write in paragraphs or their use may be confusing.”

• Band 7: “presents a clear central topic within each paragraph.”

Adding a clear topic sentence will really help you to move towards Band 7.

There is too much detail here about the laws in Denmark.  Instead of detailing the percentage of fat (a type of writing tested in Task 1) you could have discussed some of these ideas

• if increasing the price of potato chips or burgers by a small amount will really change behavior,
• if people will really switch to healthier food
• if the government would be better subsidizing healthy food
• why everyone has to pay more for milk or butter just because a few people are fat
• whether gym subscriptions for fat people would be more effective or higher health insurance premiums
• whether reduced insurance premiums or income taxes for healthier people would be better
• people should be free to buy what they want
• if governments have any business in deciding the price of food
• if unhealthy food might become a status symbol or symbol of freedom and defiance
• what the money raised would be used for
• if the food industry (not governments) should be more responsible

Overall

Overall, 387 words is much too long. You spent too long on details. Write short clear topic sentences and make sure each paragraph has a clear central topic. Have three ideas in each body paragraph. You will soon be on your way to Band 7!