Effects of consuming a high carbohydrate diet after eight weeks of exposure to a ketogenic diet

Abstract

BackgroundKetogenic diets have been utilized for weight loss and improvement in metabolic parameters. The present experiments examined the effects of returning to a chow diet after prolonged ingestion of a ketogenic diet.MethodsRats were maintained on chow (CH) or a ketogenic diet (KD) for 8 weeks, after which the KD rats were given access to chow only (KD:CH) for 8 additional weeks. Caloric intake, body weight, and plasma leptin, insulin and ghrelin were measured before and after the dietary switch.ResultsAfter 8 weeks of consuming a ketogenic diet, KD rats had increased adiposity and plasma leptin levels, and reduced insulin, as compared to CH controls. One week after the diet switch, fat pad weight and leptin levels remained elevated, and were normalized to CH controls within 8 weeks of the dietary switch. Switching from KD to chow induced a transient hypophagia, such that KD:CH rats consumed significantly fewer calories during the first week after the dietary switch, as compared to calories consumed by CH rats. This hypophagia was despite significantly increased plasma ghrelin in KD:CH rats. Finally, KD:CH rats developed hyperphagia over time, and during weeks 6-8 after the diet switch consumed significantly more calories per day than did CH-fed controls and gained more weight than CH-fed controls.ConclusionCollectively, these data demonstrate that returning to a carbohydrate-based diet after a period of consuming a ketogenic diet has post-diet effects on caloric intake, body weight gain, and insulin levels.

Hypothalamic hormones and metabolism

“…An expected consequence of the increase in fat mass is an increase in leptin because leptin levels are proportional to fat mass (Maffei et al, 1995). Several studies confirm this prediction by showing that the ketogenic diet may more than double serum leptin levels (Kinzig et al, 2005; Thio et al, 2006; Honors et al, 2009; Kinzig and Taylor, 2009; Kinzig et al, 2010), though some find no change (Kennedy et al, 2007). …”

“…Several studies show that children experience significantly slower weight gain and linear growth while on the diet (Vining et al, 2002; Williams et al, 2002; Liu et al, 2003; Peterson et al, 2005; Neal et al, 2008; Bergqvist et al, 2008; Spulber et al, 2009). Some (Uhlemann and Neims, 1972; Zhao et al, 2004; Nylen et al, 2005; Thio et al, 2006; Kennedy et al, 2007; Ribeiro et al, 2008; Samala et al, 2008; Raffo et al, 2008; Hansen et al, 2009; Thio et al, 2010) but not all (Muller-Schwarze et al, 1999; Noh et al, 2003; Thavendiranathan et al, 2003; Honors et al, 2009) studies show that rats and mice fed a ketogenic diet exhibit slower weight gain than those fed a regular diet. The inverse relationship between serum ketones and weight in children and rodents provides indirect support for ketosis being necessary for this phenomenon (Peterson et al, 2005; Thio et al, 2006; Spulber et al, 2009).…”

“…In rodents, the ketogenic diet can double fat mass as a percentage of total body mass (Thio et al, 2006; Ribeiro et al, 2008; Honors et al, 2009; Kinzig and Taylor, 2009; Kinzig et al, 2010) (Fig. 1).…”

“…This reduction in serum glucose may produce or reflect a change in insulin. Accordingly, several studies in rodents demonstrate that ketogenic diets lower serum insulin by at least 25% (Kinzig et al, 2005; Thio et al, 2006; Kennedy et al, 2007; Honors et al, 2009; Kinzig and Taylor, 2009; Badman et al, 2009). The decrease in insulin is a more consistent finding than the increase in serum leptin levels.…”

“…Serum ghrelin levels increase (Kinzig et al, 2005) or do not change in rats (Thio et al, 2006; Honors et al, 2009). In humans and rats, serum cortisol levels increase by 20% or more (Fraser et al, 2003; Thio et al, 2006).…”