Dieting atin this day and age is more popular than ever.

Some people claim that it has drastically changed their lives.

Others, however, are skeptical and call attention to the various health risks of some popular diets.

We must acknowledge that sometimes following a diet is not a matter of choice, but instead a necessity.

People with a life-threatening disease may have to cut down on the consumption of some foods and avoid others altogether.

SThe same goes for competing athletes.

Even in this case, there are some upsidebenefits to dieting.

It gives you a clear-cut plan to follow, which makes it easier to stick to itexecute.

Additionally, most diets recommend eating less fast- food and sugar, which has massive health benefits in and of itself.

First of all, despite of what many self-proclaimed specialists want you to believe, there is no magic diet that will help you get in shape in two weeks or keep you young forever.

There are many unscrupulous individuals ready to use any trick in the book to get you to buy their product.

Second, and most importantly, a lot of diets are actually dangerous for your health.

Some even demand quite radical changes in the way you eat, e.g.. For example, maybe you have to completely stop eating meat or fruit, while ts. There areis strong scientific evidence that such products are the primary source of indispensable macro- and micronutrients.

For the most part, however, just eating a variety of different foods and keeping everything atyour food intake balanced is enough to stay healthy.

Dieting atin this day and age is more popular than ever.

We must acknowledge that sometimes following a diet is not a matter of choice but aof necessity.

It's a little more elegant to mirror your choice of words. "not a matter OF choice but [a matter] OF necessity.

People with a life-threatening disease havemay need to cut down on consumption of some foods and avoid others altogether.

Same goes forThe same can be said of competingtive athletes.

Slightly more formal structure. Also "competing athletes" tends to apply to people who are actively engaged in the activity at the time. "Competitive athlete" tends to imply a person who focuses on doing the activity on a regular basis in competitions, and would likely be making those diet and exercise changes that you are referring to.

To sum up, even if in some cases following a diet can be a good choice, we need to take any dietary advice with a grain of salt.

No correction here, but using "grain of salt" in an article about dieting is a lovely little bit of word play. Kudos!

Dieting atin this day and age is more popular than ever.

"in" is the proper preposition here. The expression is "in this day and age."

Some people claim that it has drastically changed their lives.

Technically correct without "has," but sounds more natural with "has."

We must acknowledge that sometimes following a diet is not a matter of choice but rather a necessity.

Adding "rather" makes this sound a bit more natural.

People with a life-threatening disease have to cut down on consumption of some foods and avoid others altogether.;

Ssame goes for competing athletes.

Combining these two sentences with a semicolon makes sense because "Same goes for athletes" relies on the previous sentence for context. It is better to combine them so you don't have a sentence standing alone without context.

There are many unscrupulous individuals ready to use any trick in the book to get you to buy their product.

should be "there are many."

Second, and most important, a lot of diets are actually dangerous for your health.

It sounds awkward to say "dangerous for health." Usually when we talk about one's health we say "your health" and not just "health."

Some even demand quite radical changes in the way you eat, e.g. you have. For example some diets require you to completely stop eating meat or fruit, while there areis strong scientific evidence that such products are the primary source of indispensable macro- and micronutrients.

This sentence is a bit too long and the e.g. sounds a bit clunky. Reworded it here. Also, the word evidence is singular so "is" should be used instead of "are."

To sum it all up, even if in some cases following a diets can be a good choice in some cases, we need to take any dietary advice with a grain of salt.

"To sum it all up" is more often used than "to sum up" (at least in American English). "Even if in some cases following a diet can be a good choice" sounds a bit awkward. Reworded it to sound more fluid.

For the most part, however, just eating a variety of different foods and keeping everything atin balance is enough to stay healthy.

"in balance" is correct. "at balance" uses the wrong preposition.

Some people claim that it has drastically changed their lives.

Others, however, are skeptical and call attention to the various health risks of some popular diets.

People with a life-threatening disease have to cut down on the consumption of some foods and avoid others altogether.

SThe same goes for competing athletes.

It gives you a clear-cut plan to follow, which makes it easier to stick to wit.h

Sounds a little more natural to me.

Additionally, most diets recommend eating less fast-food and sugar, which hasve massive health benefits in and of itself.

SThe second, and most important, downside is that a lot of diets are actually dangerous for one's health.

Sounds more natural.

Some even demand quite radical changes into the way you eat, e.g. you have to completely stop eating meat or fruit, while there areis strong scientific evidence that such products are the primary sources of indispensable macro- and micronutrients.

To sum up, even if in some cases following a diet can be a good choice in some cases, we need to take any dietary advice with a grain of salt.

For the most part, however, just eating a variety of different foods and keeping everything at balanced is enough to stay healthy.

/Comment: I tried to write the whole text in a formal style but I failed.

Some people claim that it has drastically changed their lives.

We must acknowledge that sometimes following a diet is not a matter of choice, but a necessity.

Even in this case, there are some upsidebenefits to dieting.

I think benefits is a better word choice than upsides

There are many unscrupulousout of shape individuals ready to use any trick in the book to get you to buy their product.

Unscrupulous's definition is having no morals/being dishonest. In your case of talking about dieting, describing the individuals as unfit or out of shape fits better in context.