I should have snapped an up to date pic of him demolishing either my egg yolks or my cream today, but the camera was out of reach and I was trying to keep the bulk of the cream off of the carpet in the sitting room! Had other concerns about no lunch left for me too. Anyway...
I've been trying to make head or tail of this study, sent to me by a couple of people off blog.
It's not easy. There is no information about what was done, physiologically, to the mothers of the metabolically damaged rat pups. If you don't know that, you can't work back to what the intrauterine environment was likely to have been for the rat pups. The logical conclusion seems to be that you should not eat, when pregnant, a 50% fat diet if the rest of your non protein calories are a sucrose, maltodextrin and corn starch mix. Probably you shouldn't eat huge amounts of it either. That's a reasonable approach to life in general. If sucrose derived fructose causes hepatic insulin resistance, with hyperglycaemia from the readily available glucose, you are not going to burn fat very well. But I can't get at the data from the earlier studies by this group to see what the physiology of the dams was like.
But one of the references they did cite, which does have full text access, was this one with a beautiful summing up in the conclusion (I just love the beacon carried by the word "inappropriate" and the phrase "looked as thin as"). Talk about nailing your colours to the mast:
"In summary, this study in Wistar rats gives evidence of a metabolic imprinting of the progeny born to dams fed an inappropriate high-fat diet since 6 wk before mating, which did not became overtly obese before gestation and even lost more body weight than control dams at the end of lactation. The long-term metabolic consequence of this maternal imprinting was an altered hypothalamic leptin signaling in male and female offspring which, however, looked as thin as controls in adulthood, even when weaned onto the HF diet"
That's pretty awful. Deranged leptin signalling. And that's just on 40% fat. Imagine the awful effects of our 70-80% fat diet on our son.... Arghhhhhhh. Oh, but despite deranged leptin signaling neither the mothers nor their offspring became obese, even following the offspring through to adulthood on a high fat diet.... Hmmmmmm
So let's just skip the biased discussion and have a look in the RESULTS section. If we ignore the really clever stuff about STAT-3 signaling and gene expression, what are the end results in terms that we might observe in my son?
Table 3 of the results section is here.
First it's males at the top and females at the bottom. We want the left hand column throughout for the rats fed mostly on sugar (maternally in pregnancy and as their post weaning diet) and the extreme right hand column for the rats fed fat throughout the study. You can browse the middle columns if you want to see what crossovers do, but let's keep it simple. Many of the changes do not reach statistical significance. Just look at the trends in these small groups.
Males: High fat diet produces:
An extra 7g of body weight out of 350ish grams. Bad? Biologically significant? I weighed 120lb as a teenager. Obesity angst at 123lb? I think not.
LOWER triglycerides, probably Good.
LOWER cholesterol (who cares? But these researchers should have considered this Good)
HIGHER glucose, probably Bad, but remember physiological insulin resistance in HF feeding.
LOWER insulin. Very Good.
HIGHER leptin, hence the conclusions. Bad, but not very much higher and well within physiological limits
LOWER HOMA score. This is Very Good.
In the females the high fat feeding results are pretty much the same as or better than the chow fed rats. Especially the HOMA estimate of insulin sensitivity.
So in this study offspring of the 40% fat fed dams, fed a 40% fat diet themselves, did pretty well compared to those fed 4% fat.
How does this lead the the conclusions reached by the researchers? I dunno.
More importantly, how did the New York group (Chang et al) manage to successfully mangle the metabolism of a group of pups fed 50% fat vs those fed 25% fat? How can 40% be as good or better than 4%, but 50% be worse than 25%?
Well, I don't know. One of life's mysteries.
But I'm impressed at the skill of the Chang et al in managing to develop a model which holds up their preconceptions.
Presumably, if the study of Chang et al is correct, it explains why the Masai, Inuit and Tokelau islanders all died out of obesity when they started eating more than 40% of their calories from fat on a real food diet.
Oh, they didn't?
Back to drawing board then.
But I still wonder how she did it (Chang, that is).
Oh, and the other seriously important conclusion is that a high fat diet perinatally produces what looks to be a neurotransmitter pattern for fat preference. This is considered to be a Bad Thing. But not by me. A fat preference is a GOOD THING.
Remember Sweden! "Healthy 4 year-olds who eat lots of fat weigh less" and "More fat linked to less weight in kids study". Are you still fat phobic?
Now a sucrose preference... That would be bad, but non exposure just might lead to non preference. I hope so, but I'm not expecting Chang to find out for me.
Peter
