Functional Medicine

Lack Of Protein Drives Hunger (Part 1)

How Processed Diets Lead Us To Consume More Calories Than We Should

About Scott V Watkins, MD

Readers who are familiar with Functional Medicine will recognize the acronym SAD — the Standard American Diet.

This actually refers to a Western diet that is high in processed foods with refined carbohydrates and too much fat. Recent studies have also highlighted that the relative lack of, and seemingly decreasing amount of, protein in these ultra-processed foods actually drive us to eat more calories.

An Australian study published in March 2022 in the journal Obesity evaluated this, and explained the Protein Leverage Hypothesis (PLH). The publication adds to this concept initially proposed by University of Sydney researchers in 2005. To briefly summarize, the PLH states that humans seek a diet of approximately 15% to 25% protein. As our highly processed diets provide less protein, we remain unsatiated. Having a hunger for more protein, we end up consuming many more calories from our poor diet, in the form of processed carbohydrates and fats. Reviewing over 9,000 patients, the study showed an average protein intake of 18.4% with 43.5% of calories from carbohydrates, 30.9% from fat, 2.2% from fiber and 4.3% from alcohol. This is actually a low protein intake, and helps explain the higher percentage of carbohydrates and fats: Less protein = hunger for more protein. In an attempt to obtain that protein, we eat more, but with our poor diet choices, we end up consuming many more carbohydrates and fat while not getting the protein we need.

In October 2021, an analysis of the National Health and Nutrition Examination Survey (NHANES) data in the U.S. showed the consumption of ultra-processed foods increased from 53.5% in 2001-2002 to 57% in 2017-2018. The amount of minimally processed foods (think whole foods) decreased from 32.7% from 2001-2002 to 27.4% from 2017-2018.

As we factor in the damage these ultra-processed foods cause (leaky gut, inflammation, insulin resistance), it is easy to see why the trend in Western countries is toward obesity, heart disease, diabetes and a host of other chronic illnesses.

The international Recommended Daily Allowance (RDA) for protein is 0.8 grams per kilogram of body weight (gm/kg). In the United Kingdom, the Reference Nutrient Intake (RNI) for protein is 0.75 gm/kg. Multiple studies are beginning to recognize these numbers may be too low. One of the factors is a physically active lifestyle (PAL) that would require more protein, especially resistance training. Aging is another factor influencing whether more protein may be necessary. Sarcopenia, the loss of muscle mass and strength, is a common problem in aging populations and can lead to a decrease in activity and independence, generalized debilitation and more falls. This decreased vigor often comes when people are faced with the rigors of treatments for serious medical issues, at a time when they may be least able to tolerate those treatments.

One study published in 2008 compared protein intake at the RDA level (0.8 gm/kg) with increased protein consumption (1.1 gm/kg). This was a longitudinal observation study looking at patients 70-79 years old. The actual protein intake had shown a little variation: 0.8 gm/kg +/- 0.3 gm/kg for the RDA group and 1.1 gm/kg +/- 0.4gm/kg for the higher intake group. Over the three-year study, those in the increased protein intake group had 40% less muscle loss than those in the RDA group. The difference of 40% less loss of muscle can be the difference between a life lived fully with independence and perhaps being in a facility for one’s “Golden Years.”

To help put these numbers into perspective:

One (1) kg = 2.205 pounds.
For a 180-lb man, that equals 81.6 kg.
Using the RDA, 81.6 kg x 0.8 gm/kg = 68.6 gm of protein per day.
For a 140-lb woman, her kg weight is 63.5.
Using the RDA, 63.5 kg x 0.8 gm/kg = 50.8 gm of protein per day.

Using the protein intake evaluated in the 2008 study, which was published in the journal Nutrition:

A 180-lb man, 81.6 kg x 1.1 gm/kg = 89.8 gm of protein per day.
A 140-lb woman, 63.5 kg x 1.1 gm/kg = 69.9 gm of protein per day.

A quick Google search indicates the average weight for an American male over age 20 is 197.9 pounds, and for the average female over age 20 it’s 170.6 pounds. Thus, if these are the total grams of protein we require on a daily basis, I believe it is safe to say many of us do not get that amount — perhaps not even close.

Based on the studies we have reviewed, this leaves us with a significant protein “hunger” that we try to fill, but with our poor diet choices, we end up stuffing ourselves with too little protein, and too much carbohydrate and fat content. Consequently, we don’t satisfy our protein hunger and make ourselves obese In the process.

The next article in this series on protein will discuss when it’s best to consume it.