Nathan Pritikin devised the Pritikin diet in the 1950s after being diagnosed with heart disease. Our diet plan review explains how his eating plan drastically improved his health.

The Pritikin diet is a low-fat, high-fibre eating programme combined with exercise. It is almost entirely vegetarian, is low in cholesterol, and cuts out fat almost completely, but is a programme that requires significant commitment and changes in lifestyle. Diet meal plans recommend large amounts of vegetables and whole grain, and instead of eating three large meals a day, you will eat six smaller meals. Processed grains like white bread or quick cook rice are completely banned, as are any animal-based proteins such as meat or dairy. You will also need to keep up the exercise side of the programme by walking for a minimum of 45 minutes every day.

Medical research suggests that following the Pritikin diet reduces the risk of common illnesses, as well as having many long-term health benefits. It's also suitable for diabetics as it helps normalise blood sugar levels without having to take insulin. Although it's not promoted as a weight loss programme, losing weight is one effect of following the regime. However, critics say that the programme's rigid food restrictions mean that too little Omega-3 fatty acids are included. These are necessary to help the body digest vitamins A and D.

In the modern day version of the programme, developed by the son of its inventor, diet meal plans and recipes focus on "calorie density". Foods that have a lower calorie-per-volume ratio, such as apples and oatmeal, enable you to eat until you are full without developing excess body fat.