Lime plays as an important spices in Vietnamese dishes for it enhances the freshness of food while bringing health benefits. Any Vietnamese noodle dish/soup main course (such as Pho or Bun Bo Hue, ...) is always served with a small plate of limes and red peppers. Especially in the Southern area of Vietnam, we squeeze lime in many main courses.

The nutritional benefits of limes do not differ very much from those of lemons. They are both excellent sources of vitamin C, B6, potassium, folic acid, flavonoids and the outstanding phytochemical, limonene.

There are different many resources and information of the uses of limes/lemons if you google it. For example, from juicing-for-health.com many of lime/lemon health benefits are listed:

Asthma: Take a tablespoon of lemon juice at least one hour before each meal to relieve asthma.
Burning soles/feet: Rub a sliced lemon over the burning sole/foot/heel to relieve from pain and for toxin elimination through the pores of the feet.
Cholera: The potent anti-viral properties in lime/lemon can kill cholera bacilli within a very short period of time. Drink one part juice and one part water regularly, especially during an epidemic.
Cold: The anti-viral properties in lime/lemon fight infections and halt the progress of a cold. Take the juice of two lemons in half a liter of hot water and add raw honey to taste. Sip it slowly before bedtime.
Constipation: Drink a glass of warm water every morning with some lime/lemon juice with raw honey. Stir in a pinch of cinnamon powder. This will help your body to detoxify and relieve constipation.
Digestion: Lime/lemon juice have amazing digestive qualities that are very similar to our digestive enzymes. Thus it is effectively helps with digestion and relieve bloating and belching.
Feet, tired: After a long day on your feet, soak your feet in very warm water containing lime/lemon juice to enjoy the cooling, astringent feeling. This will also help promote deep sleep due to the relaxing action on the foot nerves.
Gums, swollen: Drink a glass of diluted fresh lime juice with a pinch of sea salt to relieve the pain of swollen gums. Use the albedo (the white matter under the peel) from the squeezed lime and rub on the gums.
Heartburn: Add two teaspoon of concentrated lime/lemon juice into a glass of warm water and drink to relieve heartburn.
Inflammatory disorders: Even though lime/lemon juice are sour and taste acidic, it is actually very alkalinizing in the body and is highly effective in the treatment of inflammatory disorders like rheumatism, arthritis, sciatica, etc. It also prevents the deposit of uric acid in the tissues, thus reducing the risks of gout.
Skin, dry: Rub the peel of a lemon on dry or scaly skin to restore softness and add moisture to the skin.
Sore throat: Mix one part lemon juice with one part water. Gargle frequently and feel its soothing effect on the throat. You may also add in a pinch of sea salt for added effect.

Can lime/lemon help with diet ( or help you burn fat?)

No, but it helps reduce fat storage!

I may trust what they say on the internet about the benefits of lime to reduce fat; however, I myself can't drink a glass of lime/lemon juice mixed with water without any sugar added. It's nasty!!!

However, It's true that Limes/Lemons have high levels of citric acid, and according to Totally Explained.com, citric acid is an important component of the Citric Acid Cycle (Kreb's Cycle), during which citric acid is involved in the breakdown of fats--as well as carbohydrates and proteins--into carbon dioxide and water.

Today, I'll show you an quickly and easily-made dish in Vietnam to make use of the freshness of lime juice but very tasty!

Bo Tai Chanh - Rare Beef Marinated in Lime Sauce

(Sorry I'm lazy with the translation, so this recipe is my modified version from foodgeeks.com)

SERVINGS

5 to 10 servings

INGREDIENTS

1 lb. beef tenderloin or eye of round, sliced paper-thin against the grain

Vietnamese crab cracker (1/2 box - deep fried in hot pan)

You may add some cooked shrimp to add the red color for decoration

Dressing
3 limes
1/4 cup good fish sauce (nuoc mam)
3 tbsp. white sugar
2 cloves garlic, minced
1 piece ginger, grated
1 dash dried chiles or 1 thai bird chile, chopped fine (suit to taste)

Garnishes
Crushed roasted peanuts or cashews
Cilantro, chopped
Basil, shredded
Mint, shredded
Scallions, chopped or shallots, minced
Fried garlic bits
Drizzle of lime juice

INSTRUCTIONS

1. Mix dressing ingredients until sugar is well-dissolved. Let stand for at least 10 minutes, up to overnight.

2. Add raw beef and 3/4 of dressing to a bowl and ensure all slices are in contact with dressing. Let stand about 10-15 minutes. (if you can't stand the taste of raw beef, then quickly stir fry them in a hot pan with 1-2 spoon of olive oil)

3. Drain beef and arrange on a chilled platter. Drizzle with remaining dressing, then sprinkle with garnishes of your choice, I recommend all of them. Serve immediately on the crackers.