| Summary: | Obesity is the most common clinical disorder and is associated with various
medical conditions in dogs. Appropriate dietary management potentially provides weight
loss in a safe, healthy, and efficacious manner. In order to elucidate whether dietary
fiber, carnitine, diacylglycerol (DAG), and low glycemic index (LGI) act on such dietary
components, a series of studies was conducted: 1) the combination of dietary
fiber/carnitine effect on short term (3 and 7 h) satiety and long term (6 weeks) canine
weight loss, 2) the combination of dietary LGI/high glycemic index (HGI) starches and
DAG/triacylglycerol (TAG) effect during a 9 week canine weight loss period, and 3) the
DAG effect on triglyceride rich lipoprotein (TRL) metabolism isolated from canine
plasma 3-4 h postprandially.
The combination of dietary fiber/carnitine supplementation decreased both food
and energy intake at 3 h post-feeding, suggesting that this combination diet provided 3 h
post-meal satiety. This combination supplement also increased postprandial plasma B-
hydroxybutyrate (BHB) at d 42 and body fat and weight loss at d 42 from baseline. This combination supplement did not alter plasma vitamin A distributions or concentrations
although it contained high vitamin A as B-carotene. In the second study, the LGI diets
resulted in a more pronounced body weight loss than the HGI diets due to lower diet
digestibilities. These data are consistent with LGI diets decreasing metabolizable energy
and consequently consuming less energy compared to the HGI diets. The DAG diets
lowered postprandial plasma TAG at weeks 1 and 8 in and increased plasma BHB at
week 8, suggesting an increase in fat oxidation. The combination of DAG/LGI decreased
postprandial total cholesterol at week 8. Lipoprotein concentrations were not altered by
diet types. Fasting lipoprotein lipase (LPL) and hepatic lipase (HL) activities were not
affected by diets. In the final study, DAG ingestion decreased TRL and plasma TAG
concentrations vs. TAG ingestion. The DAG enriched meal increased non-esterified
fatty acid, monoacylglycerol, and 1,3-DAG and decreased TAG in TRLs which may be
attributed to larger TRL particle size compared to the TAG meal. Consequently, the
DAG derived TRLs showed increased affinity of core TAG for LPL and HL in vitro.
Moreover, the intravenous injection of the DAG derived canine TRLs into mice
underwent more rapid blood clearance associated with the greater hepatic uptake
compared to the TAG derived TRL injection.
In conclusion, the combination of dietary fiber/carnitine and DAG/LGI
preferably reduced body weight and stimulated fat oxidation, which promotes overall
weight loss. The postprandial plasma TAG lowering effect of DAG is the result, at least
partially, from the efficient clearance of TRLs from blood circulation and their ability to
act as a more efficient substrate for plasma lipolytic enzymes.
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