There was recently a debate in the press about the ethical problem of society giving the individual rules to follow concerning his/her health. The reason is of course that there are societal costs involved. Smoking is such a habit that is being phased out in society seemingly successfully. Over weight (BMI=25-30) and obesity (BMI larger than 30), however, is a more sensitive subject. BMI=weight in kg/square of height in m).
I recently had a reason to research the topic of dieting. It occurred to me that the reason for the veritable jungle of dieting advice on the net and the literature is that making controlled experiments would be very difficult where you both find out which calorie deficit you should use for optimal results and on top of that which type and composition of the food to use. To do this with one single person of the same age is for example not possible. It would have to be performed on large cohorts of individuals where compliance for a standardized diet would be impossible to achieve. The problem is of major importance due to the large proportion of people that are overweight and that try to diet.
Knowing that liver glycogen is first made available when you start to fast followed by muscle glycogen which makes the dieter very happy initially because glycogen binds water, up to 4 liters in a 70kg male, which gives initial weight losses that are substantial. What is not clear from available information is how the glycogen is rebuilt, if it happens when the weight increases due to water accumulation rather than fat. It is conceivable that it can happen continuously or that it happens after the diet is over and the dieter searches his/her equilibration weight.
Thanks to detailed information on food products and databanks with food energy information it is possible to find out where your break even point is in the energy consumption of your sedentary life. Online calculators can be used to calculate your basal metabolism rate from your sex, age, height, weight and for calculation on how much energy you have to remove to get a certain weight loss per week. As a rule of thumb a pound of fat has 3,500 calories which means that you have to lose some 500 calories a day to drop 0.45kg per week. The Microsoft Excel program makes it very easy to do these chores. Losing a kilogram a month on fasting 300 calories per day would be something many people could easily do in this fashion.
The break even point, ie practicably a level of calorie intake that accounts for your basic life without exercise, can then be used to arrange for a given life style that can be maintained in this fashion. After all, it occurred to me, taking responsibility for what you eat is approximately the same problem as brushing your teeth.
I could not find information on what level of weight loss per week would be optimal. However, it is mostly recommended that people should not diet faster than half a kilogram per week. Not more than 10% of your starting weight over 6 months. The reason for this is that higher levels of calorie deficit per day than about 500 might induce a starvation mode. This is when the body starts using energy more efficiently which means that the weight loss would decrease making it less optimal for more dieting pain.
Detailed information on this important issue would be useful due to the enormous impact on the psychology of dieting. Starvation mode is dangerous because you burn lean tissue rather than fat because the body lowers the amount of the more metabolically active muscle tissue. Exercise during dieting is beneficial for avoiding the starvation mode. You can find programs calculating energy consumption for various types of exercise over your sedentary level on the net. If you walk, you use about 1 calorie per minute for every 1km/hr you walk.
Dieting regimes often discuss the possible effect of the proportion of protein, carbohydrate and fat in the diet. Hard data for this are hard to come by but it is known by athletes that a high carbohydrate containing diet where the fat content percent is about 20 is optimal. A 70kg male needs about 32g protein per day to repair. The reason for this is that higher glycogen stores are built in the muscles which give the athlete a higher durability and thus trainability. This can obviously be important for people that in general move about during the day. They will be less tired at the end of the day. However, eating becomes more boring.