Wednesday, May 14, 2008

More ketogenic diet reseach

I've pointed out recently that keotgenic diets are used to treat epilepsy and possibly benefit other neurological conditions. However each time this is mentioend the science will often say something like:

However, the mechanism(s) by which the Ketogenic Diet achieves neuroprotection and/or seizure control are not yet known.

Here is a study which makes a guess at what is going on. Increases in ATP - the basic fuel of cells

Are purines mediators of the anticonvulsant/neuroprotective effects of ketogenic diets?

Abnormal neuronal signaling caused by metabolic changes characterizes several neurological disorders, and in some instances metabolic interventions provide therapeutic benefits. Indeed, altering metabolism either by fasting or by maintaining a low-carbohydrate (ketogenic) diet might reduce epileptic seizures and offer neuroprotection in part because the diet increases mitochondrial biogenesis and brain energy levels. Here we focus on a novel hypothesis that a ketogenic diet-induced change in energy metabolism increases levels of ATP and adenosine, purines that are critically involved in neuron-glia interactions, neuromodulation and synaptic plasticity. Enhancing brain bioenergetics (ATP) and increasing levels of adenosine, an endogenous anticonvulsant and neuroprotective molecule, might help with understanding and treating a variety of neurological disorders.

And another one - look at the sentence I've put in bold in this abstract:

Effect of weight loss and ketosis on postprandial cholecystokinin and free fatty acid concentrations.

BACKGROUND: Weight regain after weight loss may not be due primarily to voluntary return to social habits but may be explained by changes in peripheral hormonal signals activating hunger and encouraging feeding behavior. OBJECTIVE: The objective of this study was to investigate physiologic adaptations to weight loss that may encourage weight regain. DESIGN: The study had a within-subject repeated-measure design [12 healthy, obese men, 33-64 y, body mass index (in kg/m(2)) 30-46] and was a clinical intervention investigation of circulating metabolites and hunger-satiety responses before and after weight loss. Measures included anthropometry (bioelectrical impedance, body weight, and waist circumference), concentrations of circulating hormones and metabolites [ketone bodies, free fatty acids (FFAs), insulin, leptin, glucose, and cholecystokinin (CCK)], and measures of hunger and satiety at baseline, 8 wk after weight loss with a very-low-energy diet, and 1 wk after weight maintenance. RESULTS: Weight loss led to a reduction in postprandial CCK secretion (P = 0.016). However, when subjects were ketotic (elevated circulating beta-hydroxybutyrate concentrations), CCK secretion was sustained at concentrations before weight loss. After weight loss, there were reduced postprandial FFA concentrations (P = 0.0005). The presence of ketosis sustained FFA to concentrations before weight loss (P = 0.60). CONCLUSION: Rapid weight loss of approximately 10% of initial body weight results in a reduction in postprandial CCK and FFA concentrations.

.....when subjects were ketotic (elevated circulating beta-hydroxybutyrate concentrations), CCK secretion was sustained at concentrations before weight loss.

What is CCK?

Cholecystokinin (CCK; from Greek chole, "bile"; cysto, "sac"; kinin, "move"; hence, move the bile-sac (gallbladder)) is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein. Cholecystokinin, previously called pancreozymin, is synthesised by I-cells in the mucosal epithelium of the small intestine and secreted in the duodenum, the first segment of the small intestine, and causes the release of digestive enzymes and bile from the pancreas and gallbladder, respectively. It also acts as a hunger suppressant. Recent evidence has suggested that it also plays a major role in inducing drug tolerance to opioids like morphine and heroin, and is partly implicated in experiences of pain hypersensitivity during opioid withdrawal.[1][2]

So reading this abstract in the light of this it seems that the weight loss causes a reduction in CCK - and therefore an increase in hunger.....unless you are in ketosis, when hunger is suppressed?

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