Weight Management & Satiety

Protein is a critically important fuel source for muscles, and branched chain amino acids (BCAAs) are particularly so. Leucine is the most abundant BCAA found in muscles, and as the body of leucine research continues to grow, so does the evidence pointing to several benefits that leucine imparts, including the regulation of skeletal muscle protein synthesis. This was demonstrated in a study where leucine supplementation in a low dose of whey protein stimulated postprandial human myofibrillar protein synthesis as effectively as a much greater dose of whey protein (1). Similarly, a low-protein mixed macronutrient beverage supplemented with a high amount of leucine was found to be as effective as a high-protein beverage at stimulating muscle anabolism (2). Furthermore, results of another study on muscle recovery suggest that increasing the concentration of leucine in an essential amino acid supplement during moderate intensity exercise may increase post-exercise skeletal muscle metabolism (3). In addition to tissue protein synthesis, leucine in combination with vitamin B6 also increased fat oxidation and insulin sensitivity and reduced oxidative and inflammatory stress, thus suggesting a potential approach in the management of obesity (4).

Leucine is an essential amino acid, and as such, it must be obtained from dietary sources, since our bodies cannot produce it. Animal proteins in general are among the best sources of dietary leucine. Eggs contain 1.086g of leucine per 100g weight, which translates to approximately 9% of its total protein content (5). When compared to other foods commonly consumed for breakfast, eggs are not as high on a gram for gram basis as oats or cheese (see figure below). However, when a comparison of leucine content is made on a per calorie basis, eggs come out looking better than most other common food sources. At only 72 calories, with 6.3 grams of protein and a high leucine content, eggs are a nutritionally- and protein-dense food source, perfect for those trying to get a little more protein, leucine and other essential micronutrients in their diets.

As noted in the dialogue from the recent fourth meeting of the Dietary Guidelines Advisory Committee, protein is notoriously under-consumed at breakfast. Given their robust nutrient profile and leucine content, eggs can be an easy fix to this nutritional shortcoming and an important protein source to consider when helping patients and clients build healthful diets.

References:

1. Churchward-Venne TA, Burd NA, Mitchell CJ, West DW, Philp A, Marcotte GR, Baker SK, Baar K, Phillips SM. Supplementation of a suboptimal protein dose with leucine or essential amino acids: effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol. 20012; 590(Pt 11):2751-65.
2. Churchward TA, Breen L, Di Donato DM, Hector AJ, Mitchell CJ, Moore DR, Stellingwerff T, Breuille D, Offord EA, Baker SK, Phillips SM. Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial.Am J Clin Nutr. 2014; 99(2):276-86.
3. Pasiakos SM, MClung HL, McClung JP, Margolis LM, Andersen NE, Cloutier GJ, Pikosky MA, Rood JC, Fielding RA, Young AJ. Leucine-enriched essential amino acid supplementation during moderate steady state exercise enhances postexercise muscle protein synthesis. Am J Clin Nutr. 2011; 94(3):809-18.
4. Zemel MB, Bruckbauer A. Effects of a leucine and pyridoxine-containing nutraceutical on fat oxidation, and oxidative and inflammatory stress in overweight and obese subjects. Nutrients. 2012; 4(6):529-41.
5. USDA National Nutrient Database for Standard Reference. U.S. Department of Agriculture, Agricultural Research Service, USDA Nutrient Data Laboratory Website. Updated Dec 7, 2011.http://ndb.nal.usda.gov/. Accessed July 28, 2014.

Nutrition Close-Up, Summer 2014 (pdf, 1.5 MB)

Articles in this Issue…

The role of the brain, ‘food cues,’ in overeating

By Kerri Boutelle, PhD

Obesity is a serious and refractory problem that is associated with multiple medical and psychological comorbities and risks. Recent data suggest that in the United States, two out of every three adults are overweight or obese, and one out of three children is overweight or obese. Obesity is associated with cardiovascular disease, type 2 diabetes, cancer, osteoarthritis, psychological impairment, poor quality of life, and all-cause mortality.
Read More >>

Vitamin D: a stronger link to health

By Taylor C. Wallace, PhD, CFS, FACN

Getting adequate vitamin D and calcium is essential for children, who need to grow strong bones, and for adults, who need to maintain strong bones and prevent bone loss. New findings
from the Women’s Health Initiative, the largest clinical trial of >36,000 postmenopausal women, confirm the safety and synergistic benefits of these two nutrients, showing a 35-38 % reduction
in hip fracture incidence 1. If you don’t get enough vitamin D, you are less likely to efficiently absorb calcium in the gut and may lose bone as you age. The development of low bone density
and/or osteoporosis later in life, which affects approximately 54 million Americans over the age of 50 years 2, is highly linked to suboptimal nutrition and physical activity patterns during young adulthood. After the age of 20-25 years, when bone growth reaches its full genetic potential, bone “withdrawals” can begin to exceed “deposits” (except in the skull, which increases in mass throughout the lifespan).
Read More >>

Complexity of individual variability in nutrition

By Tia M. Rains, PhD

One size does not fit all when it comes to health. Be it diet, exercise, or prescription medications, what works wonderfully for one person may produce little effect or even the opposite
effect in others. This is not surprising given metabolic differences between individuals. I remember observing this first-hand as an undergraduate student in a clinical chemistry course. Each
student underwent some basic blood tests and we compared results across the class. For some tests (e.g., liver enzymes), there was little variability among the students. But in others, there was quite a bit of diversity in results. For example, the blood glucose and insulin responses to an oral glucose tolerance test varied dramatically student to student.
Read More >>

New research in fight against childhood obesity

By Jamie I. Baum, PhD

The prevalence of obesity in the United States has more than doubled in adults and more than tripled in children and adolescents since the 1970s. Roughly one in three children ages 2-19 years is overweight or obese. Obese individuals have an increased risk of developing type 2 diabetes mellitus (T2DM), hypertension, and dyslipidemia. Once restricted to adults, these metabolic diseases are now being diagnosed in children. Increasing protein in the diet has been linked to improvements in glucose and insulin control, blood cholesterol, body composition, energy metabolism, as well as increased weight loss in adults. However, very little research has been focused on determining if increasing protein in the diet of school-aged children has comparable health benefits.
Read More >>

Low-carb training getting mileage with endurance athletes

By Dave Ellis, RD, CSCS

Training low” has nothing to do with altitude and everything to do with intentionally training with low glycogen stores to enhance fat metabolism. It is the latest craze for endurance athletes who seek to preserve glycogen stores by optimizing utilization of fat stores through an adaptive process during their training. This is typically accomplished by lowering carb feed rates to <3 g / kg / d for five days or more 1. Fat intake is increased to compensate for lower carb calories with the idea that intramuscular triglyceride stores go up along with enzymes necessary for fat oxidation.
Read More >>

The ongoing, seemingly endless nutrition debate about what constitutes a healthy diet just got a little hotter. In recent weeks a new book entitled The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet [1] hit bookstore shelves, and was followed by an article in the current issue ofTime magazine called “Ending the War on Fat.” The primary message of both the book and the article is that the past fifty years or so of diet advice dispensed by various health agencies, and countless research studies performed on the diet/heart disease relationship, have been mostly flawed.  And before you discount these two recent sources as the work of lay authors, it should be pointed out that a couple of well-done, albeit controversial, meta analyses out of UC-Berkeley [2] andCambridge University [3] in England largely support the principal conclusions of the book and the Time article -that current evidence does not support low consumption of saturated fats or cholesterol as antidotes to cardiovascular disease (CVD).

How did this change in thinking come about, and where might it lead us in the future? Regarding the former, the realization that fifty years of dietary advice (that was mostly adhered to by a large segment of the population) suggesting we eat less red meat, fewer eggs and less dairy products has done little to limit the rate of CVD in the U.S. and that at the same time we were becoming more and more overweight and obese as a nation, has caused many health experts to re-evaluate the data on which these recommendations were based. And what this re-analysis indicates, among other things, is that the majority of the studies on which macronutrient intake recommendations are based were epidemiological studies, which are great for hypothesis generation but marginal for establishing cause-and-effect. Worse yet, information gleaned from some of these studies have been extrapolated or inferred to help create a story that may not exist. Both the aforementioned book and Time article tell the story of how some of the data from Ancel Keys’ well-known Seven Countries Study was apparently cherry-picked so that only data from countries that supported a saturated fat/CVD relationship were included in Keys’ analysis, and countries that did not fit this paradigm were excluded.

Another point worth noting is the possible unintended consequence of food substitution: if a person adheres to dietary advice suggesting less saturated fat and cholesterol consumption, what would he/she likely add into the diet to make up for the nutritional and caloric shortfall created by removing fats? The answer is, of course, carbohydrates. Primarily refined carbs and sugars. And newer research indicates that many of the consequences of a low fat/high refined carb diet – elevated triglycerides, decreased insulin sensitivity, more small, dense LDL particles, greater vascular inflammation, increased body weight, etc. may be the real culprits in elevated CVD risk. Ironic, isn’t it, that the foods once promoted as a healthier alternative to higher fat fare may turn out to be “the bad guys” after all?

Where will this new information lead? Still too early to tell. As any nutrition professional can tell you, diet research is fickle, and alternative hypotheses on what constitutes the healthiest diet will undoubtedly change many times in the future as new data become available. One thing that seems obvious is our need for more diet-based studies, and less single-nutrient research. When single nutrients are studied outside the context of the entire diet, misinterpretations are bound to occur. For example, dietary cholesterol as a part of a diet loaded with fruits and vegetables, whole grains, and various healthy fats and proteins may be largely innocuous; the same amount of cholesterol in a high calorie, high sugar and refined carb diet may be disease-promoting.

A healthy re-evaluation of the data on which we’ve based many of our dietary beliefs is certainly in order if we’re ever to move closer to understanding what constitutes a truly healthy diet.

References:

1.            Teicholz N: The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet.Simon & Schuster; 2014.

2.            Siri-Tarino PW, Sun Q, Hu FB, Krauss RM: Saturated fat, carbohydrate, and cardiovascular disease. The American Journal of Clinical Nutrition 2010, 91:502-509.

3.            Chowdhury R, Warnakula S, Kunutsor S, Crowe F, Ward HA, Johnson L, Franco OH, Butterworth AS, Forouhi NG, Thompson SG, et al: Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Annals of Internal Medicine2014, 160:398-406.