The Mediterranean diet is basically a way of eating and focuses on eating certain kinds of foods. There are some limitations, such as rarely eating red meat, eat a little more chicken, and even more fish. There is a large focus on plant based foods, and an emphasis on exercise. However, the use of the word 'diet' is a reference to what they eat, and not a weight loss program. It's simply a healthy way of living that has been studied for many years because the people living in that region of the world have traditionally been healthier than in most other areas of the world. You can easily lose weight following a Med Diet way of living if you practice portion control in some form or another, such as counting calories, Weight Watcher Points, etc., just like any other weight loss diet. You just choose a healthier selection of foods which will make you feel better and live longer
The Sonoma Diet is a weight loss diet that was inspired
by the Mediterranean diet, though it's not the same. The author focused on the many of the main points of the Med diet and rewrote them in a way that focused on portion control with the goal of weight loss. For her version of portion control, she used a plate for guidance. You fill so much of your plate with one kind of food, another portion with a different food, etc. And of course you get red wine, because it has been shown to be very beneficial to the health of those that live in the Mediterranean region. The Sonoma Diet is designed in 'waves' which are similar to the phases in the South Beach Diet. The first wave is the most restrictive, and the next 2 waves reintroduce foods.
Maybe your local library has a copy of the Sonoma Diet that you can browse or borrow before you buy? As far as the Mediterranean Diet, there have been many books written about it and they all basically cover the basics of the way of living. There are also a lot of websites that cover this as well. Basically, if you choose between Sonoma and the Med Diet, you will pick the one that fits your needs best. If you prefer to have everything laid out for you for portion control, food selection, and like the idea of the waves to help you get food cravings under control, the Sonoma Diet might work better for you. If you prefer to do your own thing but just know how to eat healthier while you do it, then following the guidelines of the Mediterranean Diet might fit you the best.