Many diets have overlapping features, but here are some famous diets, their composition, merits and disadvantages

Mediterranean Diet

• Ranked number one as a healthy diet.
• A diet with a splash of olive oil and a glass of red wine
• Fruits,vegetables whole grains, nuts,fish,low fat constitute the diet
• Limited lean red meat
• Fish and poultry twice a week
• Low-fat milk
• Spice and herb and restricted salt
• Improves overall longevity,improves cardiac and brain health and reduces cancer
• Easy to follow

DASH diet (Dietary approaches to stop hypertension)

• Ranked second
• Hypertension and its complication is the number one killer in the world
• The concept of this diet is restriction in salt and being high in potassium
• Use of vegetable oil for cooking
• Vegetables, fruits, whole grains, nuts, fish and poultry are included
• Main thrust is on restricting salt to less than 6 gm a day

Flexitarean diet

• Ranked third
• Similar to the previous diet but predominantly vegetarian, with occasional intake of meat

Volumetric diet

• Ranked 6th
• To eat less of energy-dense foods and eat high volume to control hunger
• Food stuffs are classified into four categories according to the caloric yield
• Category 1 (very low density) like non-starchy fruits, vegetables, non-fat milk, broth soup
• Category 2 (low density) starchy fruits grains,legumes,low-fat milk, cereals
• Category 3 (medium density) meat, cheese, pizza, salad dressings,icecream, bread
• Catogory 4 (high density) crackers, cookies,chocolate candies, nuts, butter, oil
• The principle of the diet is to replace categories 3 and 4 by 1 and 2

Vegetarian diet

• Ranked 11th
• Includes lacto ovo, i.e. eggs and milk, milk products
• Vegetables, fruits, whole grains,legumes, nuts and seeds in the right proportion
• Easy to follow
• Good for diabetes, heart and weight loss

Vegan Diet

• Ranked 20th
• Diet is derived only from plants,vegetables, fruits, grains, nuts, etc
• No animal products, including milk or eggs
• Difficult to follow and, if not properly watched, can lead to nutritional deficiencies

Paleo diet

• Ranked 33rd
• Prehistoric era diet followed 10,000 years back when there was no farming
• Permits lean meat, fish, fruits, vegetables, nuts and seeds
• No grains like rice, wheat, legumes, dairy products, salt sugar, potatoes, etc
• Good for short-term weight loss
• Lowers BP and improves sugar control
• Long-term safety questionable, with nutritional deficiencies

Atkins diet

• Ranked 37th
• Developed by cardiologist Atkins
• Based on low carbohydrate, high protein and fat
• Has 4 phases:

A) induction for usually 2 weeks

Only 10 to 15 per cent of calories from vegetables

No fruits, nuts or grains or legumes

Eat lean meat, fish, eggs, poultry

B) balancing phase: add nuts and seeds

C) pre-maintenance phase: fruits and whole grains can be added

D) maintenance phase: continue for life

• Good diet for rapid weight loss, sugar control
• Can lead to weakness, headache, constipation, nutritional deficiencies
• May require medical supervision

Keto diet

• Ranked 38th
• Similar to Atkins diet
• Not in phases, restricts proteins also
• It is a low-carb, high-fat diet
• Helps weight loss, has the drawbacks of Atkins
• Difficult to follow

Indian diet

• The traditional Indian Diet is reasonably balanced with cereals, pulses, nuts, vegetables, fruits, milk and milk products and some meat
• It needs to be modified to make it healthy
• The servings of vegetables and fruits should exceed or equal the quantity of grains and legumes
• It is not necessary to eat exotic fruits or vegetables
• Leafy vegetables, brinjal, lady’s finger, radish, drumsticks, have high nutrional values
• At present the intake of grains i.e. rice and wheat is grossly out of proportion
• Whole grains like brown rice, hand-pounded rice to be preferred
• Similarly whole wheat instead of maida should be encouraged
• Millets can be eaten since they have less caloric value and better fibre content
• Vegetable oil to be used for cooking
• Low-fat milk to be preferred
• Consumption of at least 300 ml of milk or curds or milk products essential for vegetarians
• A teaspoon of ghee can be used for flavour
• Restriction of salt and sugars is important, specially avoidance of pickles and papads, if not possible to avoid use fresh and leached pickles
• Sugar can be taken upto 30 gm if you are not a diabetic
• Nuts and seeds in small quantity
• Fish and poultry if required twice a week
• Eat only lean meat
• Adopt a flexitarean approach with occasional meat
• Food faddism should be avoided to prevent nutritional deficiencies

Do not presume gluten intolerance or lactose intolerance. These are rare and require correct diagnosis before gross diet adjustments are made. Nutritional supplements are seldom required when you do not have any disease. Some of them can contain drugs like steroids. Intermittent fasting once a week may be of benefit to improve metabolism. You can also eat what you want once a while. Of course, diet has to complemented with exercise to get the best benefit.

Dr Rajan Ravichandran, Director, MIOT Institute of Nephrology, MIOT Hospitals, Chennai