By Michael J. Rudolph, Ph.D.
For the woman or athlete who takes her weight training seriously and wants results, holding too much body fat hinders optimal performance. So, gym rats and athletes strive to reduce body fat as much as they can. The most common dietary approaches used today to decrease body fat usually involve restricted caloric consumption. Unfortunately, reducing caloric intake can be grueling, especially if the food you’re ingesting doesn’t mitigate hunger to some degree.
Furthermore, reducing food intake also tends to decrease the body’s energy expenditure or metabolic rate, primarily due to a reduction in lean body mass and an enhanced metabolic efficiency. These energy-sparing mechanisms are counterproductive, and diminish the ability to burn body fat. Incorporating dietary approaches that decrease hunger and impede fat-saving, compensatory mechanisms should more readily encourage fat loss. Consequently, innovative dietary routines, supplemented with the right macronutrients and compounds that effectively improve energy expenditure and decrease hunger, should ease the difficulty from a low-caloric diet and improve the ability to shed body fat.
Intermittent Fasting Potently Burns Fat While Supporting Lean Muscle Growth
One of the more effective dietary protocols for fat loss involves the consumption of roughly 600 calories per day a few days per week, followed by normal caloric intake. This approach, known as intermittent fasting, may seem a bit extreme because of the very low amount of caloric intake. Yet, this approach strongly activates the energy-sensing molecule AMPK, resulting in fat loss above the expected amount, by simply consuming only 600 calories per day.1 This added fat-cutting effect is likely due to the cyclical nature of caloric consumption during the intermittent diet that uniquely activates AMPK for superior fat loss.
Another advantage of intermittent fasting, not usually associated with caloric restriction, is improved lean muscle growth. This is because intermittent fasting reduces caloric consumption for a brief time, which greatly decreases intramuscular fat stores.2 The decrease of fat within muscle tissue has been shown to enhance the muscle cell’s response to the muscle-building hormone insulin3, which drastically increases muscle protein synthesis, supporting greater lean muscle growth.4
High-quality Protein Loaded in Essential Amino Acids Decreases Body Fat
In addition to dietary approaches, the right macronutrients also play an essential role in minimizing body fat. One of the more well-characterized macronutrients copiously ingested to support fat loss has been protein. However, it is not just the quantity of protein in your diet that reduces body fat, but also the quality of protein consumed that has a significant effect on fat loss. Protein quality is defined as the percentage of essential amino acids to total protein consumed, and diets with greater levels of essential amino acids (protein quality) increase fat loss.
Previous studies have clearly shown higher protein in the diet decreases body fat, yet a more recent investigation by Loenneke et al.5 demonstrates that consuming high-quality protein rich in essential amino acids may be the more precise way to reduce body fat. In this study, 27 men and women had their diets monitored for the consumption of quality protein, with the threshold being 10 grams of essential amino acids per meal. At the conclusion of the study, body fat measurements were made, and the individuals who consumed the highest quality of protein had the greatest decrease in body fat.
Putatively, high-quality protein enhances fat loss because essential amino acids, especially leucine, stimulate muscle protein synthesis— leading to greater lean muscle. The increase in muscle boosts metabolic rate, which increases the consumption of fatty acids, leading to fat loss. In addition, leucine also has the ability to inactivate the energy-sensing molecule AMPK in the brain. The inactivation of AMPK in the brain decreases hunger, conceivably lowering food intake and ultimately resulting in greater fat loss.6 Of course, at the same time, leucine also inactivates AMPK throughout the rest of the body. Since AMPK stimulates fatty acid oxidation, the inactivation of AMPK from leucine intake would likely decrease fatty acid oxidation levels and therefore, fat loss. That said, it seems plausible that leucine’s ability to enhance energy expenditure and reduce hunger is greater than its negative impact on fatty acid oxidation, as leucine intake has clearly been shown to lower body fat.
Mediterranean Diet Improves Overall Health and Triggers Fat Loss
In addition to high-quality protein intake, the Mediterranean diet includes the high intake of olive oil, fish, fruits and vegetables along with a moderate consumption of dairy products. All told, this diet is loaded with additional macronutrients and compounds that reduce the risk for heart disease and certain cancers, while also enhancing fat loss.7 As a result, it has gained considerable attention as an effective fat-loss regimen, with plenty of science to back it up.
For starters, the monounsaturated and polyunsaturated fatty acids found in olive oil and fish have definitively been shown to help burn more calories. In fact, fish oil has also been shown to positively impact body composition, causing greater fat loss, especially around the waist— as subjects given fish oil had a larger reduction in waist circumference relative to controls consuming no fish oil.8 In addition, olive oil also contains a wide variety of polyphenolic compounds, like oleuropein, that enhance thermogenic fat loss for an even greater loss of body fat.9
The consumption of fruits and vegetables associated with the Mediterranean diet provides carbohydrates with a low-glycemic index that triggers a lower insulin response because low-glycemic carbohydrates don’t cause blood sugar levels to rise very quickly. So the requirement for insulin secretion is lowered. Since insulin directly inactivates fatty acid oxidation, the lower insulin levels in response to low-glycemic carbohydrate sources raises the level of fatty acid oxidation, resulting in lower body fat.10
Finally, the consumption of dairy products while following the Mediterranean diet also improves the ability to lose fat, as many scientific studies have shown that the inclusion of dairy products, like milk, in the diet accelerates the reduction of fat mass.11 Since milk is loaded with calcium, which indirectly activates the AMPK-driven fatty acid oxidation12, scientists believe that calcium is one of the key ingredients in milk that burns fat.
Milk is also fortified with vitamin D, which together with calcium, has been shown to promote greater levels of fat loss. In fact, a study by Siddiqui et al.13 looked at two different groups of obese rats that were fed a low-calcium, low-vitamin D diet or a high-calcium, high-vitamin D diet. After weeks on both diets, the rats consuming a high calcium and vitamin D diet demonstrated reduced body fat mass due to a greater level of fatty acid oxidation.
1. Tai S, Yokota Y, et al. Effects of short-term refeeding after rapid or slow body mass reduction on body composition in adult rats. Obes Res Clin Pract 2010;4, e163-246.
2. van Loon LJ, Koopman R, et al. Intramyocellular lipids form an important substrate source during moderate intensity exercise in endurance-trained males in a fasted state. J Physiol 2003;553, 611-625.
3. Larson-Meyer DE, Newcomer BR and Hunter GR. Influence of endurance running and recovery diet on intramyocellular lipid content in women: a 1H NMR study. Am J Physiol Endocrinol Metab 2002;282, E95-E106.
4. Hillier TA, Fryburg DA, et al. Extreme hyperinsulinemia unmasks insulin’s effect to stimulate protein synthesis in the human forearm. Am J Physiol 1998;274, E1067-1074.
5. Loenneke JP, Wilson JM, et al. Quality protein intake is inversely related with abdominal fat. Nutr Metab (Lond) 2012;9, 5.
6. Saha AK, Xu XJ, et al. Downregulation of AMPK accompanies leucine- and glucose-induced increases in protein synthesis and insulin resistance in rat skeletal muscle. Diabetes 2010;59, 2426-2434.
7. Sofi F, Cesari F, et al. Adherence to Mediterranean diet and health status: meta-analysis. Bmj 2008;337, a1344.
8. Bender N, Portmann M, et al. Fish or n3-PUFA intake and body composition: a systematic review and meta-analysis. Obes Rev 2014;15, 657-665.
9. Oi-Kano Y, Kawada T, et al. Oleuropein, a phenolic compound in extra virgin olive oil, increases uncoupling protein 1 content in brown adipose tissue and enhances noradrenaline and adrenaline secretions in rats. J Nutr Sci Vitaminol (Tokyo) 2008;54, 363-370.
10. Lopes da Silva MV and de Cassia Goncalves Alfenas R. Effect of the glycemic index on lipid oxidation and body composition. Nutr Hosp 2011;26, 48-55.
11. Abargouei AS, Janghorbani M, et al. Effect of dairy consumption on weight and body composition in adults: a systematic review and meta-analysis of randomized controlled clinical trials. Int J Obes (Lond) 2012;36, 1485-1493.
12. Lee ES, Uhm KO, et al. Oxytocin stimulates glucose uptake in skeletal muscle cells through the calcium-CaMKK-AMPK pathway. Regul Pept 2008;151, 71-74.
13. Siddiqui SM, Chang E, et al. Dietary intervention with vitamin D, calcium, and whey protein reduced fat mass and increased lean mass in rats. Nutr Res 2008;28, 783-790.