| Archive for The Magic Bus Trip Never get off the Bus! |
| Dan |
Increasing the fat-to-carbohydrate ratio in a high-fat diethttp://www.clinsci.org/cs/113/cs1130417.htmIncreasing the fat-to-carbohydrate ratio in a high-fat diet prevents the development of obesity but not a prediabetic state in rats Abbreviations: a.u., arbitrary units; BMI, body mass index; CV, coefficient of variation; HCD, low-fat and high-carbohydrate diet; HDL-C, high-density lipoprotein cholesterol; HFD1, high-fat and medium-carbohydrate diet; HFD2, very-high-fat and low-carbohydrate diet; HFD3, very-high-fat and carbohydrate-free diet; HOMA, homoeostatic model assessment; HOMA-IR, HOMA of insulin resistance; LDL-C, low-density lipoprotein cholesterol; NEFA, non-esterified fatty acid. Correspondence: Dr Etienne Challet (email challet@neurochem.u-strasbg.fr). Metabolic disorders induced by high-fat feeding in rodents evoke some, if not all, of the features of human metabolic syndrome. The occurrence and severity of metabolic disorders, however, varies according to rodent species, and even strain, as well as the diet. Therefore, in the present study, we investigated the long-term obesogenic and diabetogenic effects of three high-fat diets differing by their fat/carbohydrate ratios. Sprague–Dawley rats were fed a control high-carbohydrate and low-fat diet [HCD; 3:16:6 ratio of fat/carbohydrate/protein; 15.48 kJ/g (3.7 kcal/g)], a high-fat and medium-carbohydrate diet [HFD1; 53:30:17 ratio of fat/carbohydrate/protein; 19.66 kJ/g (4.7 kcal/g)], a very-high-fat and low-carbohydrate diet [HFD2; 67:9:24 ratio of fat/carbohydrate/protein; 21.76 kJ/g (5.2 kcal/g)] or a very-high-fat and carbohydrate-free diet [HFD3; 75:0:25 ratio of fat/carbohydrate/protein; 24.69 kJ/g (5.9 kcal/g)] for 10 weeks. Compared with the control diet (HCD), rats fed with high-fat combined with more (HFD1) or less (HFD2) carbohydrate exhibited higher BMI (body mass index; +13 and +10% respectively; P<0.05) and abdominal fat (+70% in both HFD1 and HFD2; P<0.05), higher plasma leptin (+130 and +135% respectively; P<0.05), lower plasma adiponectin levels (-23 and -30% respectively; P<0.05) and impaired glucose tolerance. Only the HFD1 group had insulin resistance. By contrast, a very-high-fat diet devoid of carbohydrate (HFD3) led to impaired glucose tolerance, insulin resistance and hypoadiponectinaemia (-50%; P<0.05), whereas BMI, adiposity and plasma leptin did not differ from respective values in animals fed the control diet. We conclude that increasing the fat-to-carbohydrate ratio to the uppermost (i.e. carbohydrate-free) in a high-fat diet prevents the development of obesity, but not the prediabetic state (i.e. altered glucose tolerance and insulin sensitivity). ------ Is it me, or did they gloss over the fact that the animals on the high fat diets all got fed more total calories than the ones on the high carb diet. HFD1 got 27% more, HFD2 got 40% more and HFD3 got 59% more. Even with that much more, HFD3 didn't gain any weight. |
| jeff |
Thanks Dan. Yes, they did gloss over that fact. 
And I'm not one bit surprised that the high fat, carb free rats were tested to have glucose intolerance. They were fed high fat, carb free meals for 10 weeks. It seems to me that the rats would stop producing the enzymes necessary for glucose metablolism. So of course if you then give them pure glucose and see how they react, it won't be good. |
| Dan |
HFD1 got 27% more calories and only got 13% fatter, HFD2 got 40% more and only got 10% fatter and HFD3 got 60% more and didn't get fatter at all.
"By contrast, a very-high-fat diet devoid of carbohydrate (HFD3) led to impaired glucose tolerance, insulin resistance and hypoadiponectinaemia" Doesn't make sense. This term seem to mean they have below normal levels of adiponectin (a hormone that lowers insulin sensitivity and increases fat burning.) Perhaps the truly keto adapted rat burns fat through some other mechanism. Obviously its burning fat if it kept its weight stable while they stuffed it with butter. It'd be nice to know what kind of fat they used on the little bastards. |
| Heather L |
These are all good points, but I was also wondering if the results would be very relevant to humans, anyway. What kind of diet are rats normally on in nature... i.e. what is their natural diet? Don't they usually eat mostly plants/ grains, or is that just the field mice that live around here? LOL
I should look that up. |
| jeff |
Another good point, Heather. I'm pretty sure a rat's normal diet is mostly vegetarian. |
| Badger |
Rats are true omnivores. They eat what they can find. |