HCG stands for Human Chorionic Gonadotropin. HCG diet has become very popular these days simply because it offers fast results.  Though people have a rough idea about HCG diet, you need to know the stages in order to better understand it. There are several stages of HCG diet system.
Bingeing Phase I:
I Many people think this stage is not necessary and they directly move on to the next stage. I tell most patients it is not needed. . Opposite of the overall principle of HCG diet in this stage the dieters overeat. They eat food with high calorie especially with high levels of fat. Including pizza, steak, pastas, cheeses, avocados and nuts. 
There is no limit to the number of calories or the types of foods that are eaten. Sweets, cookies, ice cream, deep fried foods, etc are all acceptable foods. Phase I is a very critical part of the diet. It is common for people to gain 3 pounds in the first two days. Don’t worry, you will lose it all in the follow 48 hours.
Low Calorie Diet: Phase II:
The second phase starts with the intake of the HCG drops along with very low calorie diet on day 3 of the diet.This is the day that you begin eating a strict diet of 500 -800 calories.You will experience some hunger during days 4-5. This is common, but will pass as the HCG builds in your system and begins to suppress your appetite. You will be surprised how much food you really do not need as you continue
through this phase.
The second phase may run as long as the dieter needs.  Dr Simeons noted that people slow their weight loss due to “immunity” to the HCG. I believe this slow down is natural due to multiple factors, including:
1. Normal response to weight loss is to slow metabolism to prevent further weight loss.
Slow downs are seen in every diet.
2. Weight loss is proportional to what a person weighs. So after a lot of weight loss one would expect a slow down in the rate of weight loss.
3. HCG diet is often limited and boring. People naturally start cheating which causes the apparent slowdown.
All of these explanations may play a role in the apparent slow down in weight loss of the HCG diet. If a person is doing well on the diet, then there are no reasons to stop.
Dr Simeons Pounds and Inches were written many years ago, before we had the numerous low calories, no sugar and no fat foods. I have added many new prepared foods. All are low calorie, with no sugar and no fat. Look at the Recipe section for selections.
You will most likely be surprised as you come to a realization of how much food you usually eat during a day that you never thought about. How often do you walk through the kitchen and “pop” something in your mouth to snack on? Most calories that add to your stored fats are the simple snacks that people eat throughout the day, even when they are not hungry. They are usually high in fat and sugar.
Phase 3: Recovery Phase
For 2-3 weeks following phase 2, the dieter needs to slowly introduce carbs. 
Rice,pasta, potatoes, sugars and other very high carbs should not be eaten.
A  full list with thumbnail pictures are given in Dr Lipman’s HCG book.
HCG Side effects: HCG side effect include headaches, irritability, restlessness, slight water retention, tenderness of breast tissue, There are some rare, severe side effects as well which include the development of ovarian hyperventilation in females.  If a user of HCG products notes any side effects it is recommended that he or she cease using the products immediately and that he or she seek out the assistance of a physician.
*As with any weight loss program, there are no guarantees for individual weight loss. Information provided herein is based on historical research, studies, and results from the many thousands of former HCG (human chorionic gonadotropin) weight loss clients. Individual success is dependent upon a variety of factors.
Phase 1: The Bingeing Phase:  
Days # 1 and #2:  These are “loading” days wherein one gorges on very high fat food. HCG is taken twice a day during this period. One of the reasons for failure latter on, is avoiding this phase. Have some fun and eat some really “bad foods.” You should be eating an extra 1000-1500 calories per day. Focus on high calorie, high fat foods including cheeses, avocados, and heavy creams. 
Two reasons for this phase are noted: One is to alert the body that extra fat calories need burning, so start those engines. Another is that this relieves any hunger and other discomfort in the first week of the diet. Many people use the weekend as their loading up days and start the 500 calorie a day plan on a Monday.
 Here are some examples
Breakfast: Cream cheese bagel with bacon and sausage, and a ham/cheese omelet.                   Have some fun, go to IHOP and have some pancakes.
Mid-morning snack: Donut with whipped cream with strawberries. 
Lunch: steak, chicken, potato with sour cream, and a roll with butter and a buttered veggie. 
Mid-afternoon snack: Ice cream with Oreos. 
Dinner: Pasta like Fettuccini, pizza, cheese garlic bread, and salad with full-fat dressing, of course, cheesecake for dessert.
Late-night snack: Ice cream or frozen cappuccino.
Once you have fat loaded for two days, you will start the restricted calorie diet. Initially it is common to have hunger cravings, but these will subside between days 5-7. Calories average about 500 per day however; you don’t have to finish all your food, as you will find that you are not hungry. Some people load up on flax seed oil during these two days; take 9000 mg a day in divided doses.