Using the Scientific Method in the Nutrition Field

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  • 0:02 Scientific Method
  • 0:44 Steps
  • 3:14 Reliability
  • 5:40 Lesson Summary
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Lesson Transcript
Instructor: Rebecca Gillaspy

Dr. Gillaspy has taught health science at University of Phoenix and Ashford University and has a degree from Palmer College of Chiropractic.

The scientific method is a systematic process that scientists follow to provide reliable nutritional advice to the public. Learn how a hypothesis is formulated and how this leads to the creation of a theory, as well as what makes a study reliable, in this lesson.

Scientific Method

Thanks to modern technology, nutritional advice is always available. The morning talk shows, the Internet and the evening news spread educational sound bites about food and nutrition across the globe in the blink of an eye. Many of these media outlets are dispensing sound advice, yet some can leave us scratching our heads.

We need a way to sift through the bombardment of nutritional information to be sure we are getting the most reliable facts, and that is where the scientific method comes into play. The scientific method is a systematic set of procedures that scientists follow to gain knowledge. In this lesson, we will learn how the scientific method is used in the study of nutrition.


To simplify things you might want to think of the scientific method as a formal way to ask questions and find answers. With this in mind, it makes sense that the steps of the scientific method start when researchers ask questions. For example, a research scientist might wonder whether people who eat an apple a day visit their family doctor fewer times a year than those who do not eat apples.

This curiosity leads to the second step of the scientific method, which is to formulate a hypothesis. A hypothesis is a proposed explanation that has not yet been tested. Basically, our scientist is making an educated guess so he has something to test. For example, he might formulate this hypothesis: 'An apple a day keeps the doctor away.'

Great! Now that our scientist has his hypothesis, he can move on to the third step, which is the experiment. This will allow him to test his hypothesis to see if it is valid or not. To do this he will compare the number of doctor visits a group of daily apple eaters make in a one-year period with the number of times a group of non-apple eaters visit their doctor over the same time period.

With this data, he is now ready for the next step of the scientific method, his analysis. This is when he gets to decide if the results from his experiment support his hypothesis. This analysis allows him to complete the final step of the scientific method, where he draws his conclusion. If his experimental results did not support his hypothesis, then he would have to conclude that the hypothesis is incorrect and go back to the drawing board.

But this is not the case for our scientist, whose careful analysis of the data brought him to the conclusion that daily apple eaters do avoid the doctor more often. He is excited about the results of his work, but nutritional advice is not set in stone after one experiment. In order for this hypothesis to be accepted by the scientific community, the experimental results must be repeated by other scientists and similar results must be observed. If this happens, then the hypothesis becomes a theory, which is a tested explanation that has been generally accepted by the scientific community.


The scientific method is a great tool for studying nutrition. It has been used to set nutrition recommendations, understand how nutrients support health and learn how nutrition supports athletic performance. Yet, in order for the scientific method to produce reliable results, there are a few factors that must be present.

First, the data must be able to be objectively measured. This means that the data collected must be able to be measured by different people. For example, the body weight of an individual can be easily measured by a number of different investigators by using a scale, whereas the opinions or testimonies of test subjects may not be as reliably measured.

Second, for the scientific method to be valid it must evaluate an appropriate group of people. For example, if you are testing the effects of a weight loss supplement on post-menopausal women, then the supplement must be given to post-menopausal women and include enough test subjects to show that the results are not simply due to chance. Basically, the more test subjects involved in a study, the more reliable the results.

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