zarrin77
Member
Interesting study.
The difference of thyroid hormone concentration is indeed significant, although one cannot be sure whether in this case a high concentration of T3 is indicative of a high thyroid function (metabolic rate).
Peat writes in "Unsaturated Vegetable Oil: Toxic": "Unsaturated oils block thyroid hormone secretion, its movement in the circulatory system, and the response of tissues to the hormone. "
So one would have to verify that the chickens with the flax seed oil diet had a higher metabolic rate.
The size of the fat pad could be an indicator, however the difference between the tallow and oil group is not really significant and even if it was, one would have to control for the absolute amount of food consumed.
I am not saying this study is meaningless, just trying to find an explanation from Peat's perspective.
Maybe others will chime in.
I understand this critique, but to be fair, this is the usual critisism here. Animal fat will never be just saturated fat, so that’s what we are going to be eating in the real world. Virgin coconut oil is different, and I do not believe it has the negative effects that other forms of saturated fat have due to the chain length, so it also cannot be studied and generalized to all saturated fat.
Anyway, here you go:
Diet-induced Thermogenesis Is Lower in Rats Fed a Lard Diet Than in Those Fed a High Oleic Acid Safflower Oil Diet, a Safflower Oil Diet or a Linseed Oil Diet
Diet-induced Thermogenesis Is Lower in Rats Fed a Lard Diet Than in Those Fed a High Oleic Acid Safflower Oil Diet, a Safflower Oil Diet or a Linseed Oil Diet - PubMed
“Rats were meal-fed for 12 wk an isoenergetic diet based on lard, high oleic acid safflower oil, safflower oil or linseed oil, and norepinephrine turnover rates in brown adipose tissue were then estimated. Whole-body oxygen consumption after the meal indicated that diet-induced thermogenesis was significantly lower in rats fed the lard diet than in those fed the other diets. The norepinephrine turnover rate in the interscapular brown adipose tissue was also significantly lower in the lard diet group than in the other diet groups. The carcass fat content was significantly higher in the lard diet group than in the other diet groups, whereas the abdominal adipose tissue weights were the same in all diet groups. These results suggest that the intake of animal fats rich in saturated fatty acids, compared with the intake of vegetable oils rich in monounsaturated or polyunsaturated fatty acids, decreases diet-induced thermogenesis by a decline of sympathetic activity in brown adipose tissue, resulting in the promotion of body fat accumulation.“
This isn’t a one-off finding. Lard and palm oil diets *consistently* get negative results compared to unsaturated fats in animal and human research.
I am also a proponent of a lower fat diet, and a whole-food diet.
Edit: Also, this “postprandial thermogenesis” is very likely correlated with thyroid hormone:
Postprandial Thermic Effect of Chicken Involves Thyroid Hormones and Hepatic Energy Metabolism in Rats - PubMed
Thermogenic Effect of Glucose in Hypothyroid Subjects
https://journals.physiology.org/doi/abs/10.1152/ajpendo.1985.249.5.E519
Norepinephrine can also stimulate thermogenesis, but norepinephrine decreases after a meal. So basal thermogenesis has multiple driving hormones (norepi and thyroid for example), but the change in thermogenesis from a meal is mostly thyroid-driven.
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