I started out with the Atkins diet. His theory is that the body's insulin mechanism goes out of order with years of refined foods rich in carbohydrates and sugars. Insulin converts carbs and sugars into fat. Eat proteins instead and you won't get fat, and your insulin mechanism will remain in good condition.
I went on the diet eight months ago along with some exercise (running), a vitamin pill a day, and lots of water. So, far I have lost 10 kilos and feel very good indeed!
There is another way to think about this diet. What kind of food are our bodies used to?
Well, Homo Sapiens appeared in Africa around 200,000 years ago. They remained hunter gatherers for around 190,000 years. About 80,000 years ago they came out of Africa through Yemen and beach combed around the world, populating every continent in the world, including the Americas around 25,000 years ago. What was their lifestyle like?
Here are some guesses.
Wake up at dawn, quick wash and hunt for food. That means running, jumping, climbing and swimming. In the process they would normally find eggs, some fruit (a little, no orchards, remember!), fish, small birds that don't fly well, small animals and insects, some edible leaves and veggies (a little, no farms, remember!). Sometimes, honeycombs and large game. All this to be shared by a tribe of around 200 people. Some snoozing in the afternoon, more hunting in the late afternoon. Sometimes intoxicants in the evening. Music, dance, sex. To bed by sunset.
This, I think, will translate to a meal of a few bites of meat or fish, some eggs and leaves. Maybe a bite of fruit. And as much water as they like.
This is what the human race ate for 190,000 years. In the last 10,000 we invented farming and started eating what is now called "regular" food. Refined carbohydrates in huge amounts. Fruits and vegetables, often processed into juices full of sugar. Drinks with chemicals and sugars. Milk and milk products (imagine trying to milk a wild buffalo!).
10,000 years is too little for a biological sytem to adapt to new nutrients. On the average, genetic changes take 20,000 years to take effect.
The result of "regular" food - strokes, heart attacks, diabetes, obesity. I suspect, barring accidents, they used to live longer than us.
They could move about 5 miles an hour, until horses got tamed. Then they could do 17 miles an hour. In the modern cities of today we move around 15 miles and hour in our expensive cars, but that's another story.
Back to the diet, I think all you need to do is to look at whats on your plate and imagine what it would have taken to get it in pre-agrarian times. If it is easy (like a piece of fowl), eat it freely. If it is difficult (like a piece of beef or a potato), eat very little of it. If it is nearly impossible (sugar, milk, flour, bread) don't touch it.
Run and jump around a bit and drink lots of water. Have lots of sex. You will be surprised how quickly your body will respond to a lifestyle it was designed for since the dawn of our species.