After the optional Phase 1 of the HCG diet you will begin Phase 2 which will take 26 to 46 days and includes the VLCD (very low calorie diet) where calories are restricted to 500 kcal per day. This is after the initial loading phase where you eat as much as you want for 3 days.
The VLCD diet might seem a bit intimidating at first, but after the first few days your body and hypothalamus will adjust, and any physical or psychological effects of consuming a lower amount of calories will start to lessen. Keep in mind that HCG will reduce your appetite substantially, so you shouldn't feel much hunger at all after the first five days of the VLCD, and remember that the HCG is providing you with the majority of the energy you need by burning abnormal fat.
Get into the routine of drinking water during the first few days
During the first few days of the VLCD you might feel slightly lightheaded as your body shifts to ketosis and begins burning abnormal fat for energy. It's very important that you drink more than a half-gallon of filtered or bottled water throughout Phase 2 so that your body can rid itself of excess ketones and flush toxins. It's easy to neglect this so be sure that you measure out the quantity of water that you need to drink each day and get into the habit of regularly drinking it. It's a good idea to keep a water bottle in close proximity to you at work and when you're at home, and it's especially important to drink more water when your work is physically demanding.
Eat three to five times per day to feel fuller
You might start to feel hungry in spite of the appetite suppressing effects of HCG. If this happens, you may need to space out your meals. Don't try to get the 500 calories in with just one or two meals. Try to eat a minimum of 3 to 5 times per day; this will keep your metabolism up and will make you feel less hungry. Again you want to be sure that you are drinking the minimum of a half-gallon of water every day as the water will also help you feel less hungry.
You might have a few minor symptoms
Changing your diet so rapidly can cause a few symptoms as your body adjusts to ketosis, and the transition will be more difficult if your diet has been high in sugar, salt and fat. So, the first few days of the VLCD might result in a headache, a small amount of fatigue, and other symptoms which are the result of your body detoxifying and also switching fuels. You can take aspirin as recommended in the Simeons protocol if you get headaches, but after the first few days the headaches should subside if you get any at all, and they are not common.
You will feel better after the third or fourth day
After the third or fourth day of the VLCD you will start to feel fine throughout the day. You won't feel much hunger if any at all, as your body has become accustomed to ketosis and will get all of the energy you need from excess fat stores. You will probably start to feel like you have even more energy than you did before the diet started, and some people experience the effect of having more energy after day two or three of the VLCD. After a few days your hypothalamus will be reset and you won't have the same desire to eat unhealthy foods. You will crave the foods on the HCG diet and be satisfied by them, and if you eat organic foods as recommended in the diet protocol you might have even more energy as your body adjusts to a cleaner source of nutrition.
Rapid weight loss during the first few days is common
The main thing you will notice once you enter the VLCD phase is that you will start to lose what will seem like an amazing amount of weight each day. Rapid weight loss during the first few days of the VLCD is common; you can expect to lose up to 1 pound per day at the beginning of the diet, and some of that weight loss will be retained water. The VLCD will cause your body to flush excess water that has been retained from eating foods that are high in sodium, carbohydrates and simple sugars, and other foods that can cause water retention. The HCG will also start to cause abnormal fat to being to be burned in large quantities right away, and the resulting weight loss will be rapid.
Don't exercise during Phase 2
You shouldn't exercise during Phase 2, especially during the first few days of the VLCD as it will make the transition to ketosis more difficult and you might have additional symptoms. If you have to exercise keep it at a minimum of 20-30 minutes of light exercise. Keep in mind that if you have an active lifestyle where you move around a lot it is just like exercising and you won't even need to consider light exercise at all. Exercise is not a requirement for Phase 2 and you will get great results even if you don't exercise at all. If you are in the habit of exercising you can always do light exercise, but you might want to wait until your body adjusts to the VLCD.
Stay positive and remember that the hunger is psychological
Some people may experience more hunger at the beginning but you have to remember that the hunger is psychological because you are getting all of the nutrients that you need through the carefully selected food choices of the VLCD plus the abnormal fat that your body is burning for energy. The hunger is mostly psychological, but once your hypothalamus has been reset you won't crave the same foods as before, and you will feel better within just a few days after your body adjusts to using fat as fuel.
Keep a positive attitude and don't worry that you are not getting enough nutrition, as the diet has been carefully selected to provide you with everything you need during the 23 or 43 day VLCD period. If you find that the first few days of the diet are difficult talk to a medical professional as there are several ways to help you adjust such as increasing your water consumption, changing the protein consumption amount for each meal, and other adjustments that can be made as needed.