Diabetes type I think doctor 

High triglycerides are usually caused by other conditions, such as:

Obesity.

Poorly controlled diabetes.

An underactive thyroid (hypothyroidism).

Kidney disease.

Regularly eating more calories than you burn.

Drinking a lot of alcohol.

Genetic predisposition; some forms of familial hyperlipidemia such as familial combined hyperlipidemia i.e. Type II hyperlipidemia

It´s possible that your substance influences the regulation of internal lipases (e.g. ATGL) in adipocytes or receptors (e.g. CD36) involved in the uptake of fatty acids and therefore the body fat decreases. The secreted free fatty acids, if not utilized in muscle or adipose tissue, are transported back to the liver and the liver might produce as consequence more VLDL. Have you looked into the liver, too?

What do you mean with increased triglycerides, > 100 or >1000?

Yes I do agree with Michael. it's possible that the compound you are using affects FFA  uptake.  

There could be several reasons, for example insulin resistance or chronic inflammation. During the acute phase of an infection, for example, TG are markedly increased. Then there is lipid dystrophy in various forms, or there could be defects in lipoprotein lipase activity, or genetically or disease-mediated increases in ApoB production. This probably covers only a part of the possibilities...

one possible explanation is that your compound affect the activity of Acyl coA:cholesteryl acyltransferase 2  (ACAT2) and as consequce this reduce the cholesterol absorption , reduce the accumilation of triglyceride and cholesterylester  in the liver ( protect against hepatic steatosis ) and increase the VLDL triglyceride .

you need detailed plasma  lipid profile ( Tg and cholesterol in VLDL, LDL and HDL) and hepatic, adipose tissue and muscle lipid ( Tg, ´Cholesterol and cholesterolester).

so if the hepatic choleserol ester level is low then check this possiblity

Most likely dietary cause of elevated triglycerides points to "excessive" carbohydrate intake coupled with insulin resistance (relative to person and degree of IR--don't know about rats); certain medications such as accutane and prednisone.also alter insulin sensitivity and may increase serum triglycerides when patients eat typical amount of carbohydrate.  Serum insulin and even glucose levels may also increase.

Conditions that result in increased Hormone sensitive lipase activity and decreased lipoprotein lipase activity.

Fatty acids are delivered to adipose by hydrolysis of triglycerides in ApoB-containing lipoproteins, primarily chylomicrons. Using oral fat challenge with and without blocking activity of LPL with tylaxapol you can determine whether the rate of hydrolysis of triglycerides is affected. Your brief description is consistent with inhibition of lipoprotein lipase (LPL) on the endothelium of adipose.  This could occur if your compound induces ApoC3, Angptl4 or Angptl3. Alternatively, your compound may be blocking elimination of those aforementioned endogenous inhibitors of LPL.  There are other possible mechanisms, but I would start with the study of LPL and its endogenous inhibitors.

Hypertriglyceridemia results from overproduction of TAG-chylomicrons from the intestine (using dietary TAG) or overproduction of TAG_VLDL from the liver (using endogenous TAG) or decreased clearance from the circulation, usually vinculated to defects in lipoprotein lipase activity. If chow intake is normal and hypertriglyceridemia is seen also in fasting periods, go to the liver as first option. And I agree with Samra, hormone sensitive lipase and insulin action in adipose tissue may give you some clues.

The compound might be enhancing hepatic VLDL secretion and inhibiting endothelial lipase activity or Tg/fatty acid uptake to adipocyte culminating in elevated triglycerides in circulation 

Undiagnosed type 1 diabetes. Have you checked glucose, insulin and c-peptide levels?