Science-Based Nutrition Part 1: Science

An Alternative to Anti-Diet

This is part 1 of my Science Based Nutrition (SBN) Series.

Science

Human nutrition (what I refer to as ‘nutrition’) is an interdisciplinary field of science-based on other fields like biochemistry, psychology, physiology, epidemiology, biology, genetics, physics, chemistry, etc.… A complex field just to understand how the body interacts with and processes the food people consume. Humans must consume food to survive making nutrition an essential area of study. There is no ‘nutrient free’ state, in any given body there are many physiological processes going on that require intake of certain nutrients. The scientific method is the best way to receive insight into these nutrients, how they interact with the body, and how this affects human health.

Evidence

Nutrition is not a guessing game but based on empirical observation and sophisticated theories. These observations and theories come from experimentation. Formal experimentation and studies collectively make up the body of evidence. The body of evidence stresses the culmination of multiple pieces of evidence to come to any conclusion, one study does not dictate the answer. One study a person pulls up from google scholar does not necessarily represent the body of evidence. If there are a hundred different studies on a topic and seventy of them said intervention X causes Y result, then the other thirty studies probably say X does not cause Y. There are more studies stating X does cause Y, this gives one good reason to believe X probably causes Y given the weight of the evidence. Weighing out the body of evidence leads to the concept called the evidence scale.

 Evidence is whatever supports a belief to some degree, making that belief more probable that it is true. In science, there is hardly ever absolute proof but there are confidence and probability of something being the case. For example, a person has a car but they are pretty sure their car isn’t spontaneously in flames, there is always a possibility their car is on fire but based on the evidence of their past experience and the fact they can see their car not on fire it’s easy to conclude their car is probably not on fire. The person weighed the evidence they had available to two different conclusions, their car is on fire or not. The evidence pertaining to their car not being on fire based on the experience of their car being fine and direct observation of the vehicle outweighed evidence suggesting the car was on fire (there was no evidence of this). So, if one puts the evidence of those two conclusions on a metaphorical scale, the scale will tip in favor of the conclusion the car is not on fire. This gives us the evidence scale, by looking at the evidence of a given topic we can reach certain conclusions if said evidence supports that conclusion over others.

Hypotheses and Theories

Let us say the car is on fire, one can hypothesize or propose an educated guess as to what happened. If that person sees a lighter fluid bottle near their car and a matchbox, that person can guess based on those observations someone put their car on fire. However, hypotheses are tentative, the lighter fluid bottle and matchbox could be there by total coincidence, perhaps the car caught on fire because of a faulty circuit. Someone cannot know whether that hypothesis is correct unless an experiment is set up. An experiment related to our example would involve dousing another car in the lighter fluid then lighting that car on fire with a match. The car burning experiment would add credibility or discredit the hypothesis someone’s car was lit ablaze via lighter fluid and match. To make sure the conclusions of the first experiment are strong, the experiment would have to be conducted numerous times (perhaps with different outcomes). 

Science is a bit trickier than guessing if cars are on fire; observation and experience can be a part of science but not everything in science is observable. In nutritional science, a person cannot directly see in real-time food molecules interacting with the body. Due to this lack of direct observation scientists must theorize. Theories are explanations that propose unobserved objects, events, forces, properties, etc. to account for an observed phenomenon. For example, if you pick up an apple then drop it, the apple falls to the ground, it falls to the ground because of this force you cannot see called gravity. No one can directly observe gravity with their eyes, it is an unobservable force used to explain the phenomenon of the apple falling to the ground.

To find out if a theory is correct it needs to be tested. This test must be difficult and involve making a bold prediction. A clever prediction that can validate the theory. Scientists do this when they conduct experiments, nutrition scientists are not any different. A nutrition-related example includes the CICO model to explain body mass changes. CICO as a model is complicated but the outcome seems simple: those in a caloric deficit will lose weight, while those in a caloric surplus will gain weight. In the most tightly controlled trials, scientists can accurately predict body mass changes using this model. Predicting changes in body mass is bold and this is tested by clever experimentation.

Hypotheses and theories sound similar but they are different. Overall theories are elaborate explanations, in science, these explanations are supported by the body of evidence. Hypotheses on the other hand are more so guesses based on what is seen, they are not fixed. Think of it this way, CICO is a theory supported by multiple pieces of evidence and a specific hypothesis related to that in a paper can be… those who go on a low or high carb diet but consume equal calories and protein will lose almost the same amount of weight. This specific guess is a hypothesis that could be in a study but the theory behind it is CICO. Theories are generally broader, and one can make specific hypotheses based on these theories.

Scientific Values

Outside of evidence, hypothesis, and theory, modern science also has a set of values or norms. These norms outlined by Robert K. Merton are called Mertonian norms. There are four norms which are communism, universalism, disinterestedness, and organized skepticism.

1. Communism refers to the fact intellectual property in science should be open access to all scientists, this means no secrets to promote collaboration. For example, when scientists replicate the studies of other scientists, they are able to do so because the methods, data, results, etc. are accessible.

2. The second norm is universalism, which means scientific progress should be independent of political attitudes and personal attributes of its participants. Stated simply, science should be as objective as possible and apply to as many people as possible regardless of differences; no one defies the laws of gravity because they are tall.

3. Disinterestedness states that scientific institutions should act for the benefit of science itself and not for personal interest. This is the idea behind the peer review process, by having fellow professionals scrutinize their peers' work the product (the study) should be more honest and improved.

4. The last norm is organized skepticism, this norm entails that scientific claims should be scrutinized critically before being accepted, scrutinized in terms of methodology and codes of conduct. This leads back to the idea theories need to be tested and make bold predictions, we must scrutinize theories and claims in science.

   These norms can apply to all sciences including nutritional science. The norms in modern science give us an insight into its very nature. This nature includes collaboration, openness, objectivity, and self-correction. 

Rational Thinking

Finally, there is an individual responsibility we all share when dealing with science. This responsibility or “moral duty” is to think rationally. Rational thinking includes listening to the evidence and using valid logical reasoning. The opposite of rational thinking is just believing something based on the first article you read, popular opinion, and first impressions from social media. Some philosophers even argue rational thinking is a moral obligation or ‘duty’. An argument proposed by philosopher W.K. Clifford, suggests our beliefs influence our actions which can affect others. Therefore, false beliefs can possibly harm others and we have a duty not to harm other people (if not murder would not be illegal), so we have a duty to avoid false beliefs and believe what is true. 

For example, a car salesperson knows a particular car is old, needs extensive repair, and should not be driven, but through convincing themselves and wanting to make money they sell it to a person as is. That person gets into a car accident with that car and dies. The car salesperson had a moral duty to listen to the evidence the car was no good and should not be sold. The car salesperson had no right to believe the car was okay to be sold as is. The salesperson had a moral duty to listen to the evidence that the car should not have been sold. We do not have the right to believe whatever we want as our beliefs have practical consequences. It is our moral duty to use good reasoning and justify our beliefs with evidence; we have a duty to think rationally.

Science gives us the best evidence to justify our beliefs related to nutrition. So, we have a moral duty to use good reasoning and justify our beliefs about nutrition. Practitioners and professionals must take this into consideration when giving information and advice related to nutrition. Professionals should focus on thinking rationally.

Conclusion

To tie in all the concepts, we talked about and relate them back to nutrition, CICO will be used as an example. The CICO model is a theory that explains changes in body mass based on the physical law of thermodynamics. We cannot directly see with our own eyes changes in body heat-related to metabolic activity which over time leads to weight loss or gain but scientists are clever. Through well-constructed study design, direct measurements of metabolic activity, and repeated studies, researchers can predict with accuracy changes in body mass.  Many specific hypotheses related to caloric intake and caloric expenditure have been put to the test via experimentation, the model holds up despite these different experiments. Researchers can predictively cause changes in body mass by manipulating calories ingested and calories expended. Thus, the theory of the calories in calories out (CICO) model is most likely closer to the truth than any other explanation because it has been tested and used to make bold predictions about body mass.

There are many high-quality studies supporting the CICO model, the evidence scale tips in favor of the CICO model over other explanations for body mass changes. Many of the studies supporting this conclusion can be replicated which fits into the communism norm. CICO predicts body mass changes for many different demographics of individuals so it can be described as universal. The researchers in many of these papers contain no known conflicts of interest which exemplifies disinterestedness. Numerous studies have been criticized and scrutinized by experts in the field, but the model still holds, CICO has survived the organized skepticism of nutrition experts. 

As a rational thinker, one must accept CICO is probably true because it is justified by the evidence and is logically coherent. One has a moral duty to accept CICO as probably true; another explanation like insulin or carbohydrate intake affecting body mass outside of CICO is not logical and not justified by the evidence that is there. One must reject the latter claim (insulin/carbs) while accepting the former (CICO).

This article is meant to give you the tools to think about science. The scientific method is the best path professionals have towards gaining knowledge. Science has a set of norms associated with it encouraging collaboration, transparency, and progress. People also have a moral duty to use good reasoning and justify their beliefs with the best evidence, which so far is science. However, science does have limitations as individual differences cannot always be accounted for in the body of evidence. The next part on individuality will address these considerations and what professionals should do about these considerations.