Eating Habits That Improve Health and Help with Weight Loss and BMI

Susan Dudley, PhD, Sarah Pedersen, MPP, Caitlin Kennedy, PhD, Natalie Rosseau, National Center for Health Research

The latest research shows that measuring your waistline and keeping your BMI (body mass index) at a reasonable number will help keep you alive and healthy.[1] Research also shows that certain foods improve your health even if they don’t help you lose weight. This article will focus on eating habits that help you lose weight, but will also include information about the kinds of foods that are good for your health even if they don’t affect your weight.

Let’s start with the obvious: Sticking to a healthy diet in order to lose weight is hard for almost everyone. Keeping track of calories and fat can be confusing, and the nutrition labels on the foods we buy aren’t always that helpful. How are consumers supposed to figure out which diet advice is just hype – that ultimately doesn’t contribute to better health – and which advice offers good, medically sound information?

Here are some basic guidelines to keep in mind:

  • Calories matter
  • Serving size matters
  • Fats and cholesterol matter
  • Fruits, vegetables and whole grains matter
  • Exercise matters
  • Sticking to it matters

The Key to Losing Weight is to Eat Fewer Calories than You Burn in a Day- But There is More to it than That

Simply increasing your activity level might be enough if you only need to lose a few pounds to get your BMI into a healthy range. Most of the time, however, eating fewer calories is also going to be needed. Scientists have found that, in order to lose weight, a person must burn more calories than they consume.[2] Unfortunately, calories add up quickly!  For example, have you eaten at a fast food chain recently?  To work off the calories from a double cheeseburger, extra large fries and a 24 ounce soft drink – about 1500 calories – you would have to run for two and half hours at a ten minute mile pace! (For more information, see Fast Food Facts: Calories and Fats).  And some chain restaurants offer meals that have much more calories for lunch or dinner than an average person should eat in an entire day!

What happens if you exercise without lowering the calories you’re eating? A 2009 study found mixed results: some lost a significant amount of weight while others gained weight.[3] Although some weight loss strategies are effective for some people but not others, eating fewer calories and increasing exercise is most likely to help most people shed pounds.

Eating Fewer Calories Doesn’t Necessarily Mean Eating Less

The trick to dieting without being hungry is to choose foods that contain fewer calories and also fill you up. An example would be having a piece of fruit instead of fries with lunch.  It helps to remember that not all foods are created equal!  Some foods, such as nuts, are high in nutrients and essential vitamins, while others lack nutritional substance, such as products containing added sugars. “Nutrient-dense food” provides substantial amounts of vitamins and minerals and relatively few calories, but leaves you feeling fuller while also supplying valuable fuel for your body.  A person is more likely to stick to a diet if calories are nutrition-dense and offer variety.[4]

Empty calories from foods with processed and refined sugars, such as candy, pasta and bread made from white flour, and many energy drinks and soft drinks, leave you hungry again soon after, craving more food.  In contrast, the “complex carbohydrates” in vegetables, whole-grain breads and cereals, and low-fat yogurt and milk, provide long-lasting nutrients, improve digestion, help stabilize blood sugar, and keep your energy at an even level.  Although fruits are also considered simple carbohydrates, they contain vitamins and nutrients that occur naturally, unlike those found in processed and refined foods.

A 2011 study in the respected New England Journal of Medicine found that certain foods were linked to weight change more than others.[5] After following participants for an average of 17 years, researchers found that gaining weight was most strongly linked to foods such as potato chips, sugar-sweetened beverages, and red meat.  People who ate more vegetables, whole grains, nuts, fruits, and yogurts were less likely to gain weight over the years, even though some of those foods are quite high in calories.

What about low-carb diets versus low-fat diets? A 2014 study compared the effects of both diets on body weight and cardiovascular health. They found that the low-carb diet was much more effective than the low-fat diet for losing weight and reducing cardiovascular risks.[6] So hold back on the white bread, but don’t feel bad about eating some olive oil.  But if you want to maintain that weight loss, remember that variety in your diet as well as exercise are also important.

Don’t Assume that Foods Marketed as “Healthy” Really Are or Will Help You Lose Weight

Don’t fall for the “health halo” effect: assuming that all foods at restaurants marketed as “healthy” or all foods of a category labeled “healthy” (e.g., salads) are actually better for you.  Research shows that customers at fast food restaurants underestimate the calories in their meals [7] and most consumers underestimate the calorie content of foods that are labeled “low-fat.”[8] For example, if you look at a bag of potato chips, you will probably see that the “low fat” ones almost have the same number of calories as the regular chips made by the same company.

The choices that will keep your calories down are not always obvious.  For example, a 2013 study found that adolescents ordered about the same number of calories at Subway as they did at McDonald’s.[9] Try to check the nutritional contents of your meal options and make an informed decision. If nutritional information is not posted in the restaurant, it is probably available on the restaurant’s website.

Eating 5 Small Meals Is Not Better than Eating 3 Larger Ones

For several years, some experts have claimed that eating 5 or 6 times a day can be a better way to lose weight than eating only 3 times a day.  However, the latest research indicates that is not true.[10]

Studies have found that eating off of smaller plates or bowls helps people eat less, because most of us tend to fill our plate and then finish what is on it.[11],[12] Unfortunately, portion sizes for restaurant meals, baked goods, other prepared foods, and even homemade meals – everything from breakfast muffins to a plate of spaghetti – have grown to very unhealthy proportions in the last few decades. This is contributing to the obesity epidemic.

In addition to adjusting your portion size, limiting the hours when you eat can also help you maintain a healthy weight. In a study published in British Journal of Nutrition in 2013, researchers followed a group of healthy men for four weeks. They ate their normal diets during all four weeks, but for 2 of those weeks, they fasted for 11 hours at night (from 7 pm to 6 am). The study found that under the time-restricted conditions, the men consumed approximately 200 fewer calories per day and lost weight during the two weeks of nightly fasting compared to the two weeks when they did not fast at night. The researchers believe that it was the combination of few calories and night-time fasting that resulted in the weight loss.[13]

What About Fats?

Recent research has shown that eating foods high in cholesterol don’t necessarily contribute to a person’s cholesterol levels.  The past focus on fats is also being questioned, especially in light of an investigation indicating that the original reports that blamed fats were written by researchers paid by the sugar industry.[14]

Fats are high in calories, but some fats are more dangerous for you than others.  The least healthy ones include saturated fats and of trans fats. These tend to be the kinds of fat that are solid at room temperature – like the fat in meat products, butter, margarine, shortening and lard – and the fats that come from baked goods and fried foods.  The fats that are good (in moderation) are “unsaturated” or “polyunsaturated” fats. These tend to be liquid at room temperature, like canola oil, olive oil and some of the other vegetable oils. There are exceptions, however, such as coconut oil, which is high in saturated fats. Diets such as the Mediterranean diet, which includes more unsaturated fats and plant-based foods, can lower the chances of cardiovascular diseases. So, for people who find it difficult to stick with a low-fat diet, such as a vegan or vegetarian diet, there are other healthy alternatives.[15] Check the nutrition label before you buy, to be sure that you’re choosing the product with the lowest possible saturated fat content.

Eat More Fruits, Vegetables, Whole Grains, and Low- or No-Fat Dairy Products Every Day

There are many good resources to help you learn about healthy eating, such as the US Department of Agriculture website at My Plate. Nutritionists at the Harvard School of Public Health have similar (but not identical) healthy food guidelines. What these diets have in common includes recommendations to:

  • Aim for at least five servings of fruits and vegetables a day. Usually, the more colorful the fruit or vegetable, the more nutritious. For example, dark green spinach has more nutrients than light green iceberg lettuce. In 2023, an analysis of studies of 2372 adults with mean ages 20 to 67 reported that a vegan or vegetarian diet can help people reduce their risk of developing cardiovascular diseases.[15] However, research has also shown that any diet that replaces at least some fats, carbohydrates, and foods high in added sugar with fresh fruits and vegetables is likely to improve your health.[16]
  • Try and choose whole grain cereal, pasta, rice, and bread. Many foods that claim “whole wheat” or “whole grain” on the front of the package actually contain very little, but breads that are truly high in whole grains now give the exact amount in a very obvious place on the label.  Be sure to see if the amount listed is for one slice or two – in many cases, a “portion” is listed as 2 slices for the amount of grains but only one slice when listing calories per portion!  And don’t be fooled by bread color: dark brown breads are often colored with coffee or other dyes, not whole grains.
  • Avoid food that is high in sugar, such as pastries, sweetened cereal, and soda or fruit-flavored drinks.
  • Reduced-fat or no-fat (skim) milk, reduced-fat cheese, and low-fat or no-fat yogurt are good sources of the protein and calcium we need. Try to eat 2-4 servings of low-fat or no-fat dairy products each day.
  • Fruits and vegetables often cost less than unhealthy foods.[17],[18] By buying healthy food options, you’re doing both your body and your wallet a favor!

Exercise Does Burn More than Calories

Increasing the amount of exercise you do each day means you burn more calories to help you lose weight.  And it doesn’t take much; just 30 minutes of moderately strenuous daily exercise helps prevent heart disease, which is the #1 killer of women and men in the U.S..[17] The exercise you choose doesn’t need to be elaborate either, or even take place in a gym.  Walking, biking, swimming, or gardening can do the trick, and getting a friend or family member to exercise with you can turn this into a valued part of your daily routine.  Learn more about the health benefits of physical activity and how to get started from the CDC.

Staying Healthy is a Life-Long Proposition

Don’t think about dieting as a short-term weight loss goal.  Instead, ask yourself the question: How long do I want to live and how sick do I want to be?  Scientists have found that one of the keys to success is to think about these goals every day.[18] For example, people who get on a scale and check their weight daily are more successful at keeping their weight under control than people who don’t.[18]

Don’t Waste Your Time and Energy and Money on “Quick Fix” Solutions

For some people, there may be faster ways to lose weight than following the diet suggestions listed here.  But those quick solutions tend to be temporary; even bariatric surgeries don’t necessarily provide long-term solutions.  Learning to eat in a healthier way allows you to sometimes indulge in foods that aren’t so healthy, while still being healthier than you ever were before, and living longer.

All articles are reviewed and approved by Dr. Diana Zuckerman and other senior staff.

  1. For more information about BMI and how it is calculated, see Obesity in America: Are You Part of the Problem?
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