Fig. 12.1
Example of abdominal image (umbilical region) of first year college American football player before and after 1 year of intentional weight gain
While many studies have investigated the influence of overfeeding, for ethical reasons most of these studies were based on a short-term overfeeding intervention. Thus, there are few studies involving a long-term overfeeding intervention. In the 1960s and on through the 1980s, several long-term overfeeding studies were conducted and revealed that body weight gain was associated with decreased glucose tolerance, the development of hyperinsulinemia, and increased insulin resistance (Sims et al. 1968; Olefsky et al. 1975; Welle et al. 1986). Later, in the 1990s, in order to investigate not only the influence of long-term overfeeding but also to evaluate genetic influences, Bouchard et al. (1990) conducted an overfeeding study on monozygotic twin pairs. In the experiment, 12 pairs of young adult male monozygotic twins were overfed by 1,000 kcal per day (50 % CHO, 35 % fat, and 15 % protein), 6 days a week, for a total of 84 days during a 100-day period. Significant individual differences were observed on the degree of body weight gain (4.3 kg to 13.3 kg). There was roughly three times more variance across pairs than within pairs (p < 0.05) with respect to body weight, percentage of fat, fat mass, and subcutaneous fat. Moreover, the variance across pairs for the amount of abdominal visceral fat was six times greater than within pairs. Additionally, the increase in total body fat was correlated with gains in abdominal subcutaneous fat but not with the changes in visceral fat. These findings suggest that a person’s genotype is an important determinant of adaptation to a sustained energy surplus (Bouchard et al. 1990). This same research group also reported (Oppert et al. 1995) that insulin (but not glucose) secretion increased both at fasting and after 100 days of overfeeding as measured by the oral-glucose tolerance test. Thus, it was suggested that long-term overfeeding puts athletes at risk of becoming insulin resistant. Furthermore, persons who showed an increased insulin production after overfeeding also gained more subcutaneous fat. However, the increased insulin production did not influence the gain in visceral fat (Oppert et al. 1995). These investigators also found that there is more variance between pairs than within pairs for the change in insulin production during the fasting state after 100 days of overfeeding.
It seems that there are significant genetic influences on body composition and metabolic changes induced by overfeeding. However, most of these studies on these genetic effects were conducted on the same participant group, so the findings may not apply to other ethnic group with different dietary habit and genetic backgrounds. As one example, Japanese are known to reduce the function of insulin production and develop diabetes at a lower BMI (23.1 kg/m2) than Caucasians (Ex: 29.4 kg/m2 in United Kingdom) (Sone et al. 2003). This difference may be caused by either a different genetic background and/or a different life style. For example, the typical Japanese diet involves more carbohydrate and less fat. Thus, it is quite important to perform similar long-term investigations on persons of different ethnicities and with different genetic backgrounds.
12.5 Preventive Measure of Cardiometabolic Risk for Heavy Athletes
12.5.1 Diet
The Australian Institute of Sports has recommended increasing the nutritional intake by 500–1,000 kcal per day for athletes who want to increase their muscle mass (Australian Institute of Sport 2009). In general, the diet should be balanced, not only with an adequate mix of protein, fat, and carbohydrate (PFC), but also including the minerals and vitamins that are necessary for efficient body building (Rodriguez et al. 2009). In reality however, it is always a big challenge to control the energy balance. Nagasawa et al. (2013) conducted a weight gain program that involved dietary intervention. They showed that with a proper diet, FFM increases without significant increases in body fat mass are possible. Their study utilized Japanese college rowers who, for 12 weeks, received a 1,000 kcal/day positive energy supply with a nutritional component generally modeled according to the guidelines of the American Dietetic Association, the Dietitians of Canada, and the American College of Sports Medicine (Rodriguez et al. 2009). The subjects gained 3.8 kg (1.2 kg body fat and 2.6 kg lean body mass) with no change in fasted plasma cholesterol, triglycerides, or glucose (Nagasawa et al. 2013). The subjects’ diet had a PFC balance of 13.2 %, 28.8 %, and 58 %, which is similar to the ideal PFC composition recommended for the general Japanese population (Ministry of Health, Labour and Welfare of Japan 2012). Thus, even for athletes who are trying to build muscle, the recommended PFC diet composition does not need to be different from a typical diet. All of the meals were typical Japanese style home-made dishes prepared daily by the dietitian. Moreover, the Japanese diet is characterized by a wide variety of available foods and a versatility of cooking methods which makes it relatively easy to provide the necessary energy and nutrients sources, and match them with each individual athlete’s needs and preferences.
Food choice has an influence on the metabolic health of athletes practicing overfeeding. One study overfed subjects by 850–900 kcal with either candy or peanuts for 2 weeks. The study found that only the candy group had a significant increase in body weight; this increase was mostly due to fat accumulation. The candy group also developed an unfavorable plasma lipid profile and showed signs of insulin resistance. These untoward effects were not seen in the peanuts group (Claesson et al. 2009). Candy is largely composed of sucrose, a short-chain carbohydrate. It is thus easily digested and absorbed. On the other hand, while peanuts are high in protein and fat, the fat is “good fat”, that is, mostly monounsaturated and polyunsaturated. Therefore, the food choices of athletes during overfeeding have a major effect on which body compartments gain weight, and how the weight gain affects metabolic health. Therefore, in order to achieve an efficient and healthful increase in body weight, it is important to meet with a certified dietitian to seek professional advice on a proper diet for overfeeding. Utilizing a dietary assessment with a dietary record is an ideal tool to evaluate dietary content and dietary habits. This can provide information from which athletes can receive accurate and effective advice that meets their needs.
12.5.2 Body Composition Assessment
Regular monitoring of body composition is also very important for successful weight gain. Such monitoring can help the athlete and supervisory personnel decide whether the current weight gain regimen is adequate. Body mass in relation to height is the most basic anthropometrical measurement, and can easily be used in the field. Body mass index (BMI), calculated by dividing an individual’s body mass (in kg) by the square of their height (in m2), is used to assess weight status for overweight and obesity in routine situations. However, BMI cannot distinguish between mass of body fat or muscle mass and thus is not appropriate for use with athletes in order to evaluate their body fat status (Nevill et al. 2006). Calculating fat mass based on body fat percentage is a more suitable method for judging how fat an athlete’s is. Measurements of FFM allow an accurate assessment of muscle mass changes. Bioelectric impedance analysis (BIA) and skin-fold thickness can both be used to measure body fat percentage. These two methods do not require expensive equipment and are relatively easy to utilize. Therefore, they are suitable for monitoring daily, weekly, or monthly body fat percentage changes in the field. A BIA device with a tetrapolar or more electrode arrangement has a better accuracy than does a BIA device with only a bipolar electrode arrangement (Bosy-Westphal et al. 2008). For the more detailed or precise measurements, dual energy x-ray absorptiometry (DXA), densitometry with air or water, and ultrasound are recommended if these are available (Ackland et al. 2012). These latter methods require a testing facility with elaborate testing equipment, along with trained technicians and staff members. Thus, these methods may only be available a few times a year. In order to quantify visceral fat, MRI and CT scan are ideal methods to use, but these methods are only available at sophisticated laboratory facilities and thus not generally accessible to athletes. Therefore, estimation equations of visceral fat by abdominal circumference or DXA are also available (Kaul et al. 2012; Rankinen et al. 1999)
12.5.3 Biochemical Assessment
Even though it may be difficult to perform appropriate biochemical tests, perhaps due to budgetary limitations, it is nevertheless highly recommended for high risk athletes such as for athletes working on extreme weight gains and/or those who need to maintain a large body mass (ex. body mass of >100 kg or BMI of 30 kg/m2 or above). Such biochemical assessments can help to screen athletes at risk, detect athletes with improper dietary habits, and prevent irreversible cardiometabolic illnesses or events (Haskins et al. 2011). The most important indicators in a lipid profile are levels of triglyceride, total cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol. Insulin resistance, which tends to occur during the early stages of metabolic disease, can be assessed by fasting blood glucose and insulin via the HOMA-IR.
12.6 Conclusion
Due to a long period of overfeeding, many heavy athletes are at risk for body fat accumulation. This can lead to the development of insulin resistance and an increased risk of cardiovascular and metabolic disease. Moreover, when heavy athletes retire and stop training, they quickly join the high cardiometabolic risk population unless they lose weight. In fact, Sumo wrestlers and the linemen in American football have a shorter longevity than the general population. Therefore, it is very important for coaches and trainers to understand these health risks and the consequences of overfeeding, and importantly, the proper approach for increasing body weight. Diet composition is extremely important, and can determine whether weight gain is healthy or detrimental to health. Thus, seeking advice from certified dietitians and conducting careful dietary assessments are beneficial. Monitoring body weight and composition are critical to achieving positive health and strength in body building. Precise body compositional assessment and biochemical tests can help detect unhealthy weight gain and thus avoid the development of irreversible cardiovascular and metabolic maladies.
References
Abernethy WB, Choo JK, Hutter AM (2003) Echocardiographic characteristics of professional football players. J Am Coll Cardiol 41(2):280–284. doi:10.1016/s0735-1097(02)02633-5 PubMedCrossRef
Ackland TR, Lohman TG, Sundgot-Borgen J, Maughan RJ, Meyer NL, Stewart AD, Muller W (2012) Current status of body composition assessment in sport review and position statement on behalf of the ad hoc research working group on body composition health and performance, under the auspices of the I.O.C. Medical Commission. Sports Med 42(3):227–249PubMedCrossRef
Allen TW, Vogel RA, Lincoln AE, Dunn RE, Tucker AM, Natl Football League Subcomm C (2010) Body size, body composition, and cardiovascular disease risk factors in NFL players. Phys Sportsmed 38(1):21–27PubMedCrossRef
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