A new year is upon us. Whatever else might be happening in the world, and something always is, life must go on. For many of us the new year is also a time of making ‘resolutions’ about what we will do differently from what we did in the past.

Of the many changes or improvements we want to make in our lives, one of the more important ones is to live a healthier life style. From a visual perspective, perhaps, the most obvious sign of not being healthy is being grossly overweight.

Many of us that believe that they are overweight decide to lose weight as a new year’s resolution. To do that they turn to some diet or the other that can help them lose weight. And make them look healthier and perhaps more attractive.

What state of weight is considered attractive is very often a matter of personal choice. From a medical perspective, the measurement referred to as the body mass index (BMI) is often used to determine if a person is in the ‘right’ weight group.

BMI is based upon a person’s height and weight. Generally speaking a BMI of eighteen to twenty two is considered normal. Around thirty we are getting to what we call ‘morbid obesity. And below eighteen is definitely starting to be underweight.

Morbid obesity is a problem that can lead to many undesirable medical conditions. But the modern ‘fad’ diets are not really meant for the very obese and even if they lose weight over a relatively short period of time they will most likely put the weight back on eventually.

Before I go any further, I want to make an important point. Weight loss diets are not the same as a healthy diet. Whatever proponents of particular weight loss diets might claim, these diets are not meant for people that do not have a weight problem but just want to eat stuff that helps them stay healthy.

First then to some of the weight loss diets. They can be divided into a few basic groups. First are those that depend on portion control and their off shoot, calorie control. These are basically about ‘consuming fewer calories than what a person will normally burn up.

An average adult who is not exercising regularly or working at a job that requires physical exertion will need around two thousand calories a day. The major problem with diets where we eat fewer calories or smaller portions is that these diets will leave us feeling hungry. You can eat all the lettuce or cabbage that you can but the body knows better.

The one common thing among all weight loss diets is that they all require discipline. And some added physical activity definitely helps the weight loss project along. However, none of these diets are good or healthy diets during a normal life.

Another form of diet that is becoming fashionable in this group is the fasting diet. This does not entail prolonged periods of fasting but rather eating only during eight hours in a day and not eating anything during the other sixteen. All diets in the fewer calorie group require discipline and the willingness to go hungry.

The other major group of diets is where a particular food group is cut down on. The three major food groups are carbohydrates (bread-sugar), proteins (meat) and fat. The most famous diet that restricts fats is the Dr Ornish diet that saw its heyday in the anti-fat days thirty years ago. So far I am not aware of any well-known diet that restricts proteins.

In this connection a historical note is in order. Some forty years ago, doctors declared that fat consumption was bad since it increased the risk of heart disease. So people cut back on the fat and started consuming more bread and sugary drinks to fill themselves up. That led to an epidemic of obesity and of Type-2 diabetes. And that led to an even greater incidence of heart disease than in the fat-eating old days.

More recent research suggests that fats we eat are not all that bad as far as heart disease is concerned. More importantly it is the increased consumption of carbohydrates (carbs) that has led to many modern medical problems. So it is not surprising that some of the more popular modern weight loss diets restrict the consumption of carbs.

The first widely used low carb-diet was the Atkins Diet. The idea behind the low carb diets is twofold. First of course fewer carbs mean fewer calories consumed. The second advantage in terms of weight loss is that when enough carbs are not available to provide the body energy, the body will ‘burn’ the stored fat to produce energy.

Here I must admit that Atkins is the only weight loss diet I have ever used a few decades ago. And yes it works well to lose weight and to keep it off. One advantage of the low-carb diets is that most of them do not restrict the number of calories consumed so the dieter is not hungry all the time.

Another low carb diet that became quite trendy a decade or so ago was the ‘Paleo Diet’. It is a diet that my father’s oldest brother, a graduate of King Edward Medical College (now KEMU) circa 1930 used to push. More recently the diet was popularised as the Paleo Diet.

The concept behind the Paleo Diet is that the human body is still stuck in its original form as it was before the advent of civilisation. So the best diet for it is whatever humans ate ten thousand years ago. That means everything except cultivated grains, sugar, dairy products since dairy animals had not been domesticated yet, and other foods that are now produced or ‘manufactured’ for human consumption.

The major problem with the ‘Paleo’ part of this diet is that we don’t really know what was being eaten by our ancestors ten thousand years ago. And surely humans in Asia were eating something different from those in Europe or in sub-Saharan Africa.

The much more popular diet these days is the Keto Diet. Keto is short for ketones or ketosis. This diet takes low carb to the extreme. Basically less than twenty percent of all calories consumed should be from carbs and most calories should come from fat. The carbs include bread, sugar, most dried fruits and many fruit juices, and anything you might want to buy from your favourite bakery. Even a single normal sized Chaunsa mango would probably exceed the daily carb restriction.

What this diet does is that it throws the body into a state where fatty acids in the body fat become the primary source of energy. This is ketosis. One unfortunate side effects of this diet is that when in a state of ketosis, you will have a ‘fruity’ breath odour, sort of like nail polish removers.

The one common thing among all weight loss diets is that they all require discipline. And some added physical activity definitely helps the weight loss project along. However, none of these diets are good or healthy diets during a normal life.

To sum it up, fewer ‘refined’ carbs is a good idea. More nuts and fruits and vegetables are a good idea. Plant based fats (like olive oil) are preferable to animal fats (butter). And fish and poultry are better than red meat, though some red meat once in a while is not a bad idea. And more colourful a fruit or vegetable is, the better it is for you.

The writer has served as Professor and Chairman, Department of Cardiac Surgery, King Edward Medical University