Diet and Nutrition 饮食和营养

饮食和营养是非常重要? Yǐnshí hé yíngyǎng shì fēicháng zhòngyào?
因为快餐不够营养 Yīn wéi kuàicān bùgòu yíngyǎng
然后我们营养不良Ránhòu wǒmen yíngyǎng bùliáng
我们需要多吃天然鱼，肉和蔬菜 wǒmen xūyào duō chī tiānrán yú, ròu hé shūcài
因为天然食物的酶 Yīn wéi tiānrán shíwù de méi
否则，我们有健康问题 Fǒuzé, wǒmen yǒu jiànkāng wèntí

Why Diet and Nutrition is important?
Because natural food lacks of nutrition.
And then we suffer from malnutrition.
So we need to eat more natural food.
We need to eat more natural fish, meat and vegetables.
Because natural food has enzymes.
Or else we will have health problems.

Your Chinese is good, but still have some problems.

and others  has helped to correct it.

here is my Chinese version.

为什么合理膳食和均衡营养很重要呢？

因为快餐（natural food?)不够营养

（经常吃）我们就会营养不良

所以我们要多吃天然食物

我们要多吃天然的鱼类、肉类和蔬菜

因为天然的食物中含有酶

（没有这些酶）我们就会出现一些健康问题。

one of differences between  English and Chinese is there're more verbs in Chinese. 

好好学习，天天向上~

Diet and Nutrition 饮食和营养

为什么（why）饮食和营养非常重要? Yǐnshí hé yíngyǎng shì fēicháng zhòngyào?
因为快餐不够营养 Yīn wéi kuàicān bùgòu yíngyǎng
然后我们就会营养不良Ránhòu wǒmen yíngyǎng bùliáng
所以（so）我们需要多吃天然鱼，肉和蔬菜 wǒmen xūyào duō chī tiānrán yú, ròu hé shūcài
因为天然食物种有酶 Yīn wéi tiānrán shíwù de méi
否则，我们就会有健康问题 Fǒuzé, wǒmen yǒu jiànkāng wèntí

Why Diet and Nutrition is important?
Because natural food lacks of nutrition.
And then we suffer from malnutrition.
So we need to eat more natural food.
We need to eat more natural fish, meat and vegetables.
Because natural food has enzymes.
Or else we will have health problems.

Diet and Nutrition 饮食和营养

饮食和营养是非常重要的? Yǐnshí hé yíngyǎng shì fēicháng zhòngyào?
因为快餐营养不够 Yīn wéi kuàicān bùgòu yíngyǎng 

然后我们就会营养不良Ránhòu wǒmen yíngyǎng bùliáng
我们需要多吃天然的鱼，肉和蔬菜 wǒmen xūyào duō chī tiānrán yú, ròu hé shūcài
因为天然食物中含有酶 Yīn wéi tiānrán shíwù de méi
否则，我们就会有健康问题 Fǒuzé, wǒmen yǒu jiànkāng wèntí