Protein and Weight Loss

Recently I was asked by the staff at Dynamic Chiropractic to referee some of their water-cooler discussions regarding nutrition. Topping their list was this one about protein and weight loss: "Why is protein important for weight loss and how much should I eat (to lose weight)?" Before I answer, I would like to share a few thoughts on weight loss in general.

Weight Loss: A Tricky Topic

I believe the topic of weight loss is much more confusing, contentious, complicated and controversial than it should be – for a number of reasons, including the following:

• The marketing of diets, exercise plans, fitness equipment and a huge array of nutritional supplements is a billion-dollar industry that is very competitive.
• The Information Age we live in produces a constant stream of new research that is rapidly disseminated, selectively edited, commonly misinterpreted and excessively extrapolated – usually for secondary financial gain.
• The biochemical and physiological diversity of people means there is more than one path to the top of the weight-loss mountain.

To lose weight, there must be caloric deficit, period. Caloric deficit is achieved by eating fewer calories, burning more calories or a combination of both. Now we are ready to address the question about protein and weight loss.

Why Is Protein Important for Weight Loss?

When people lose weight, it is a combination of lean mass (muscle) and body fat. When people say they want to lose weight, what they actually mean is that they want to lose fat. It is impossible to lose only fat, but:

Consuming enough protein can reduce muscle loss at the expense of fat loss in varying degrees, depending on the person. This can be amplified with exercise targeted at the muscles a person does not want to lose.

Protein can satisfy hunger with a greater degree of effectiveness than fats and carbs in many (but not all) people.

Dietary protein requires a higher percentage of the calories it provides to metabolize than carbohydrates and fats. It can raise a person's metabolic rate for as long as 10-12 hours. (See Table 1)

Table 1: The Thermic Effect of Food Protein: 20-30 percent of calories ingested Carbohydrate: 5-10 percent of calories ingested* Fat: 3-7 percent of calories ingested *When carbs are converted to fat (lipogenesis), it requires ~20 percentof the calories.

Please note that the numbers in Table 1 vary widely from person to person. To complicate matters even more, the vast majority of calories we ingest are mixed. A fair estimate is that 10-15 percent of the calories we eat are used to metabolize the other 85-90 percent of calories.

How Much Protein Should I Eat (to Lose Weight)?

There is no exact answer to this question because "just enough and not too much" is quite variable. The amount of protein a dieter should eat is the level that reduces the most body fat and least muscle in a way that best moderates the degree of hunger. This number depends on age, sex, genetics, activity, sleep, stress and more. Ask 10 weight-loss professionals this question and you'll get a variety of responses.

Table 2: ProteinRecommendations (Grams Per Kilogram of Body-Weight Per Day)
Age / Scenario	Protein
Infants	1.5-2.0
Children 1-6	1.2
Children 7-14	1.0
Women 15 and older	0.8
Men 15-18	0.9
Men 19 and older	0.8
Hospitalization	1.0
Pregnancy lactation	1.0
Endurance - athletes	1.2-1.4
Strength - athletes	1.6-1.7
Surgery	1.5
Multiple traumas	1.5-2.0
Severe burns / sepsis	2.5

Now look at Table 2 and notice there is no recommendation for weight loss. When we look at weight-loss studies that compare different amounts of protein, the results are the average of individual responses. In other words, when we see a conclusion that the group that ate X protein lost more weight than the group that ate Y protein, not everyone in group X will lose more than everyone in group Y.

Finally, when a person asks me this question, I will ask them, "How much protein are you eating now and how much protein were you eating when you gained the weight?" In most cases they cannot answer either question, so giving them a number is meaningless until I determine their current intake and the results they are experiencing.

The Best Advice

Confused? Don't be. Just remember that to lose body fat, every step and every bite count every day. My rule of thumb for protein is this: If a person is losing weight and maintaining their exercise strength, endurance and recovery, they are getting enough protein. And that means, if you look at Table 2, they are getting no less than what is recommended for athletes, which is around double the RDA of 0.8 g/kg/bw/d. Next month, we will continue this discussion by examining a specific study on weight loss, exercise and different levels of protein.