As the owner of several weight loss ebooks and weight loss web sites I am often asked, “What are the best all around diet foods?”

My first response is to tell people that there are no magic diet foods that will help you lose weight fast, and it is important to understand that most people must make lifestyle changes that include a permanent change in their diet (not a fad diet, or temporary diet), and exercise must play a role in any weight loss program.

Once people understand these basic elements to any weight loss program I feel much better explaining to them what I believe are the best diets foods in existence because what you eat will have a big effect on how quickly you lose weight, and more importantly, how long you keep the weight off.

There are certain foods that you really should be eating on a regular basis. They come from all food categories, but every one of these diet foods has one thing in common: they pack a lot of nutritional punch into their calories. Here's a list of five diet foods that will help you stay healthy and lose weight.

1. Whole grain breads

If you've been paying attention to latest weight loss fads, you know that carbs are the current diet buster. Many weight loss programs claim that if you just stay away from all carbs you'll lose weight no matter what else you eat. That's not only wrong, it's downright dangerous for both your health and your diet.

Instead of cutting out carbs, you should be aiming to reduce carbs to a healthy portion of your diet - which most doctors agree is about 50-60% of your caloric intake. That means that if you're on a 1500 calorie a day diet, you should be striving to get about 900 calories a day from grains, fruits and vegetables. Whole grain breads pack a lot of nutritional value. Replace your two slices of white toast with 1/2 a cup of oatmeal or whole grain cereal, and for about the same number of calories, you'll be getting three times the vitamins, amino acids and roughage that your body needs to function. You'll feel full far longer, too - because you've given your body something to work on that will take a while to digest.

2. Fish

Eat at least three servings of fish per week. Fish is low in fat, is high in protein, and provides something that most other proteins don't - omega 3 fatty acids. Omega 3 is one of the main building blocks in your cells. If your body doesn't get enough Omega 3 fatty acids, it will try to build cells from other fatty acids. The problem is that those cells are not as flexible, and not quite the right shape. Among the cells that aren't quite right are the ones in your brain that help control impulses and tell your body what it needs. By providing enough Omega 3 fatty acids for your body to use, you'll be healing the damage done through years of poor diet. And since fish, as a general rule, has fewer calories than most meats, you'll be saving calories as well. Just remember that you're replacing portions of meat with fish, not adding them to what you already eat.

3. Spinach

Spinach is one of the lowest cost sources of nutrition you can give your body with 13 calories and 2 grams of carbohydrate in 2 cups of chopped raw spinach. Every serving gives you folic acid, manganese, beta-carotene, protein, lutein (a potent anti-oxidant), magnesium, vitamin C and vitamin K. You can eat it raw in salads, steamed as a side dish, or sautéed in a tiny bit of oil for a different taste, and still get all the nutritional benefits.

4. Olive Oil

Have you every heard of the Mediterranean diet? Well, as it turns out, olive oil is a mono-unsaturated fat that is the primary source of fat in the so-called Mediterranean diet. Your body does need a little fat to process vitamins and use them properly. It contains antioxidants, flavonoids, beta-carotene and vitamin E, among other things. One tablespoon has a whopping 125 calories, but drizzled on a 13 calorie spinach salad with a little lemon juice and some garlic, you still have a meal with less than 150 calories - and a whole lot of healthy fuel for your body.

5. Pink Grapefruit

With only 40 calories in half a grapefruit, you're getting 45 mg of vitamin C, lycopene, pectin, beta-carotene and potassium. It's versatile and tasty. Eat it as is for breakfast, or toss it into a salad with spinach for an extra punch to perk up the nutritional quality of your diet.

As stated earlier, the best weight loss plan combines a healthy lifelong diet with daily exercise. And, your diet should not be based around any single one ingredient. The best way to lose weight is to eat a healthy variety of foods to make sure that you get all the essential nutrients that you need each day. The diet foods mentioned above are five of the best diet foods that should be included as part of any weight loss program and diet plan.