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Body macronutrient composition is predicted by lipid and not protein content of the diet

“…One measure of reproductive investment in males is testes mass, but this is often difficult to study as it would require sacrificing males in studies where lifespan is the key trait of interest. In mice, it has been shown that testes mass is only reduced at high restriction levels, suggesting testes are protected against the effect of DR (Mitchell et al, 2015). The same study reported a marginal effect of protein restriction on testes mass (Mitchell et al, 2015), with a further study reporting increased testes mass on high protein:carbohydrate ratios (Solon-Biet et al, 2015).…”

“…However, a different study found little to no effect of changing dietary protein:carbohydrate ratio on body fat mass (Mitchell et al, 2015). In Drosophila melanogaster, body weight and lipid-free bodyweight increased with increasing protein:carbohydrate ratio of the diet, with carcass lipid content highest on a dietary protein:carbohydrate ratio of 1:2 (Lee, 2015).…”

“…In mice, it has been shown that testes mass is only reduced at high restriction levels, suggesting testes are protected against the effect of DR (Mitchell et al, 2015). The same study reported a marginal effect of protein restriction on testes mass (Mitchell et al, 2015), with a further study reporting increased testes mass on high protein:carbohydrate ratios (Solon-Biet et al, 2015). However, very few other studies look at the effect of dietary macronutrients on testes mass.…”

“…Calorie restriction is well known to affect body weight (McCay et al, 1935) but is also suggested to affect body composition, particularly adiposity (Colman, Roecker, Ramsey, & Kemnitz, 1998;Hempenstall, Picchio, Mitchell, Speakman, & Selman, 2010;Mitchell et al, 2015;Muzumdar et al, 2008;Picard & Guarente, 2005) and relative organ size (Mitchell et al, 2015;Selman et al, 2005). In fact, it has been suggested that a reduction in adiposity is the primary mechanism through which calorie restriction acts to extend health and lifespan (Barzilai et al, 1998;Muzumdar et al, 2008;Picard & Guarente, 2005).…”

“…In fact, it has been suggested that a reduction in adiposity is the primary mechanism through which calorie restriction acts to extend health and lifespan (Barzilai et al, 1998;Muzumdar et al, 2008;Picard & Guarente, 2005). In mice, for example, adipose loss due to calorie restriction occurs in a graded manner, mirroring that of lifespan extension (Mitchell et al, 2015). However, contradictory evidence suggests that fat loss under calorie restriction provided no benefit or was detrimental to lifespan (Chiba et al, 2014;Liao et al, 2011;Park et al, 2017).…”