The U.S. Department of Agriculture's (USDA) food pyramid system (www.mypyramid.gov) provides a good start by recommending that the bulk of your diet come from the grain group—this includes bread, cereal, rice and pasta— the vegetable group; and the fruit group. Select smaller amounts of foods from the milk group and the meat and beans group. Eat few—if any—foods that are high in fat and sugars and low in nutrients. The amount of food you should consume depends on your sex, age and level of activity.
Not getting enough fiber can lead to constipation and can raise your risk for other health problems. Part of healthy eating is choosing fiber-rich foods, including beans, berries, and dark green leafy vegetables, every day. Fiber helps lower your risk for diseases that affect many women, such as heart disease, diabetes, irritable bowel syndrome, and colon cancer. Fiber also helps you feel full, so it can help you reach and maintain a healthy weight.
Carbohydrates should provide 45%–65% of your daily calories. Most of those calories should come from the complex carbohydrates in high-fiber and unrefined foods, such as bran cereal and other whole-grain products, brown rice, beans and other legumes, and many fruits and vegetables. These carbohydrates are digested and absorbed slowly, so they raise the blood sugar gradually and don't trigger a large release of insulin. People who eat lots of these foods have higher HDL ("good") cholesterol levels and a lower risk of obesity, diabetes, and heart disease. A good amount of soluble fiber in the diet lowers LDL ("bad") cholesterol, and high-fiber diets reduce the risk of intestinal disorders ranging from constipation and diverticulosis to hemorrhoids. Some studies have shown that fiber may help reduce the risk of colon cancer. Men need more fiber than women: 38 vs. 25 grams a day before the age of 50 and 30 vs. 21 grams a day thereafter.
This study secretly took place in the hospital cafeteria and helped thousands of people develop healthy eating habits without changing their willpower or motivation in the slightest way. Thorndike and her team utilized a concept known as “choice architecture.” Choice architecture is just a fancy word for changing the way the food and drinks are displayed, but, as it turns out, it makes a big difference.
A spokesperson for optimal nutritional intake is the well-known biochemist Bruce Ames, who proposed the "triage theory of nutrients," in which enzymes responsible for cell maintenance functions evolved to have lower affinity for the essential vitamin and mineral cofactors than the enzymes responsible for short-term survival, to preserve life during times of famine. 
Folate is most important for women of childbearing age. If you plan to have children some day, think of folate now. Folate is a B vitamin needed both before and during pregnancy and can help reduce risk of certain serious common neural tube birth defects (which affect the brain and spinal chord). Women ages 15-45 should include folate in their diet to reduce the risk for birth defects if one becomes pregnant, even if one is not planning a pregnancy.
Most vegetarians eat milk products and eggs, and as a group, these lacto-ovo-vegetarians enjoy good health. A healthful vegetarian diet falls within the food pyramid guidelines offered by the USDA. However, meat, fish and poultry are major sources of iron, zinc and B vitamins, so pay special attention to these nutrients. Vegans (those who eat only plant-based food) should consult a health care professional about adding vitamin and mineral supplements; make sure you consume sufficient quantities of protein, vitamin B12, vitamin D and calcium.
To help you learn how to eat healthfully, start with the U.S. Department of Agriculture's (USDA) dietary guidelines system, which you can find at http://www.mypyramid.gov. The MyPyramid system, which looks somewhat like the familiar food pyramid of old, offers guidance based on individual needs and replaces "serving" recommendations with actual amounts of food. It also emphasizes the importance of balancing nutritious (and tasty!) food choices from all food groups every day with daily physical activity.
Nutritional supplements are products to aid you when you are not getting enough nutrients from your meals. Most common supplements used by people today are multivitamins, protein shakes and meal replacement shakes. In todays times where people are so busy and just don't have the time to sit down to a meal supplements have become then next best thing. These days they have supplements for just about anything from fish oils, Vitamin B or fat burning. While most of these supplements will help you some of them are not good for you. So always consult your doctor first before taking any supplement.
To assure supplements have sufficient quality, standardization, and safety for public consumption, research efforts have focused on development of reference materials for supplement manufacturing and monitoring. High-dose products have received research attention, especially for emergency situations such as vitamin A deficiency in malnutrition of children, and for women taking folate supplements to reduce the risk of breast cancer.
Calcium. As well as leading to osteoporosis, not getting enough calcium in your diet can also contribute to anxiety, depression, and sleep difficulties. Whatever your age or gender, it’s vital to include calcium-rich foods in your diet, limit those that deplete calcium, and get enough magnesium and vitamins D and K to help calcium do its job. Learn more »
Nutritionists are always saying to eat more vegetables, so cook them in a way that takes them from ho-hum to yum. "I even think that steamed veggies can be very boring!" says Ilyse Schapiro, a greater New York City-area registered dietitian. Always incorporate high-flavor add-ons to jazz up veggies, like sautéing with olive oil and garlic, or spraying them with olive oil before throwing them in an oven with salt, pepper, and garlic powder. That way, you don't equate "healthy" with "tasteless," a mindset that will knock you off the veggie bandwagon fast. Another tip: buy a spiralizer and make zucchini noodles. Topped off with a rich tomato sauce, you'll feel like you're eating pasta.
Notice that alcohol isn't included in a food group. If you drink alcohol, do so in moderation, up to one drink per day for women and two drinks per day for men. Alcohol offers little nutritional value, and when used in excess, can cause short-term health damage, such as distorted vision, judgment, hearing and coordination; emotional changes; bad breath; and hangovers. Long-term effects may include liver and stomach damage, vitamin deficiencies, impotence, heart and central nervous system damage and memory loss. Abuse can lead to alcohol poisoning, coma and death. Pregnant women should not drink at all because alcohol can harm the developing fetus and infant. According to the March of Dimes, more than 40,000 babies are born each year with alcohol-related damage. Even light and moderate drinking during pregnancy can hurt your baby. If you are breastfeeding, discuss drinking alcohol with your health care professional. After clearing it with your doctor, you may be able to have an occasional celebratory single, small alcoholic drink, but you should abstain from breastfeeding for two hours after that drink.
Some people choose their cheat days to actually be cheat meals. So, one day they could have a cheat breakfast (i.e. pancakes), then a cheat lunch on another day and then a cheat dinner or dessert, and so on. While this works for some people, I found this allows me too much flexibility in my eating schedule and I start to cheat more and more because I justify it’s a cheat meal. Rather, on a cheat day, I have the whole day to get it out of my system and then move on. And it’s pretty darn glorious, let me tell you.