Triathlon is a great way to get into better shape. But diet AND exercise are important when it comes to losing weight. Losing weight is hard! And everyone's body is different so what works for one person won't work for another. But here are some pointers to help get you started.
First, there are some of you (especially females) out there who are at a healthy weight and DON'T need to lose anything! So, for those of you, appreciate how terrific you are! Instead of focusing on weight, focus on other factors as you get into better shape. Focus on how you can run farther and faster and how strong you feel. Focus on what your body can DO, and not what it LOOKS like. That's way more important and rewarding. Check out your heart rate and blood pressure and watch it drop over the weeks of cardio training. Don't be surprised if you gain weight as you increase muscle mass. That's fine. You're not gaining fat b/c your jeans will still fit the same.
On another note, as you begin training more seriously, you might need to eat more because you're burning more calories and increasing your metabolism. I'm like this. I eat 6-7 small meals a day every 2 hours or so. I try to plan them out so they're healthy, small meals. It's when I get voracious that I make poor choices. When I do a 10-mile run, I burn 1000 calories right there so I need to replenish them. It's not uncommon for me to eat 2500-3000 calories a day.
However, it's important to listen to your body's cues and hunger pains, and only eat when your hungry. Unless you're an elite or professional athlete, you do not need to worry about changing your diet. Just focus on eating healthy and listening to your body. You don't need a bunch of Gu or energy bars unless you're doing an Ironman triathlon. Otherwise, if you're trying to lose weight, you'll just eat what you've burned off and be back where you started.
Okay, here are my tips to help you get started (remember--I'm not a professional so see your doctor).
1. Small, consistent changes over time.
You have to do this for a lifetime so forget dieting. Try doing small things that are easy changes to make. Make 1 change a week and be consistent. Focus on eating HEALTHY instead of less. For instance, try switching to skim milk instead of whole. Losing weight is hard, but you shouldn't have to go hungry. Ever.
2. Moderation. There is no such thing as a forbidden food.
Nothing is off-limits. However, some foods are calorie-dense and don't fill you up that much so you want to eat less of them. Allow room in your daily calorie-budget for your favorite foods (like chocolate--my favorite!) I like to think of total daily calories like the money I have in the bank. I have a daily allowance. I choose what to spend my calories (money) on, and when they're used up, that's it; I don't get any more food. So if my limit is 1800, I better choose wisely so I'm not hungry by the end of the day.
3. Calories in-calories out=total net calories (what you'll gain or lose)
It doesn't matter WHAT you eat; it's how MUCH. If you eat lettuce all day long but end up eating more than you burn, you'll gain weight. So forget all the diet stuff.
4. Have a plan. Keep a food journal.
This is absolutely the best way to keep track of what's going in and what's being burned off. You'll be surprised at how much you eat when you're not hungry and may not even realize. I've included a link above to help calculate the number of calories in the food you eat and how much you burn when you exercise. It's a good place to get started. Note when you eat because you're bored or have had a bad day at work. For instance, I love ice cream after dinner late at night so I try to replace this with another enjoyable activity, like taking a bath or petting the bunnies. Also, try brushing your teeth and waiting 20 minutes. If you're still craving food, then you're legitimately hungry. Learn to eat only when you're hungry.
Plan out what you're going to eat the night before. Pack lunch and snacks when you go to work. I bring a healthy microwaveable meal, a turkey sandwich on wheat bread, apricots, bananas, granola bars, apples, and yogurt. The key is to never go anywhere without having some food with you. Then, you never have a chance to get famished and run to McDonald's.
1. 3500 calories = 1 pound
2. complex carbohydrates (think fiber) and food with high water content fill you up more without giving you all the calories (e.g. brown rice, fruit, apples, oatmeal).
3. low-fat dairy fills you up with less calories too (skim milk, low-fat yogurt, certain cheeses--mozzerella).
4. lean beef and chicken are full of great protein that keeps you full and happy, but the portion sizes should be smaller than carbohydrates (think the size of a deck of cards)
5. avoid simple sugars (sugary cereals, white bread, candy)
6. forget soda or sugary juice drinks--if you want something other than water, drink diet. Otherwise you're just wasting calories.
Hope this helps! Please let me know if you have questions.