If you missed our live online chat with John Whyte, M.D., author of AARP New American Diet, read the transcript of the conversation.

Comment from Mimi: I am morbidly overweight, extremely tired all the time, no energy, depressed and the main caregiver for my grandmother. I need to lose weight and exercise but don't know where to start. Please help.

See also: Caregiving Resource Center

John Whyte: I often recommend to patients that they make changes in either food or exercise but not both at first. So let's start with food. Here are three changes you can make over a few days or a couple of weeks and you will see weight loss:

1. Limit beverages to only coffee and water. Water is naturally filling — it stretches your stomach, and that sends signals to your brain that you are full even though water has no calories. Water helps aid in the digestion process, which allows your body to absorb nutrients more effectively. And drinking water during a meal keeps your mouth busy, thereby taking you longer to eat.

2. Eliminate any food that is white unless it's low-fat dairy. I'm overgeneralizing a little, but by this I basically mean white bread, including pastries and cakes, as well as white rice. These are the processed grains that I want you to avoid. It's these processed foods that are one of the main causes of obesity and subsequent disease.

3. Eat breakfast every day. And this means a "real" breakfast — not a bagel and coffee.

I'm going to give you some specific breakfast recipes to make this easy but you should know that you might need to get up a few minutes earlier to prepare it and eat it. Believe me, it is worth it. Many people will say they are not hungry in the morning; I was like that for a long time. I barely ate anything and was always in a rush to get to the office. So I started with something small, like two pieces of whole wheat toast, and then over a few days built up to eating a variety of fruit, yogurt, fiber cereal and eggs. Now, I almost never leave home without taking some time to eat breakfast.

Eating a healthy, nutrient-dense breakfast is probably one of the best changes you can make to ensure success. And don't replace eating no breakfast with eating a breakfast of highly processed simple carbs — that's just one bad habit for another.

Comment from Debbie Aguer: Can I mix and match the daily meal plans or must I eat the three meals and snacks as they are put together?

John Whyte: Mix and match is definitely OK. The key is to eat three smaller meals a day and two snacks. As long as you eat healthy foods from the AARP New American Diet, it's OK to pick and choose your specific meals. Personally, there's three or four healthy foods I stick with for breakfast and lunch. So go ahead and mix and match. Just make sure they're healthy choices! I love oatmeal, so I'll eat that every day for about a month. Then I'll eat Greek yogurt with blueberries and walnuts every day for a week. For lunch, I might eat chicken breasts three days a week, and I go through periods of time when I eat tuna fish on rye bread. So again, find some foods you like from the meal plan, and go ahead and stick with them. We are all creatures of habit!

Comment from Rachel: Between work and caregiving, I'm constantly on the go, and taking time to make healthy meals goes to the bottom of the list. I find myself grabbing fast food on the way here or there. How can I make healthier choices at fast-food restaurants?

John Whyte: It's a common misconception that eating healthy takes a lot of time and work. The reality is that it takes more planning — you need to have the food around. For instance, fresh fruit is the original fast food. What's faster than eating a banana or an apple? And people often are fearful of cooking fish — but it actually only takes about 10 minutes — quicker than the round-trip to most fast-food restaurants. If you have to go to fast-food restaurants, please avoid anything fried; never say "supersize."

Next page: What are the three best foods you can eat? The worst? »