The health benefits of fish oil are well known, but it may not be known how much it is good for you.

Fish oil has been used as a replacement for saturated fat in foods for centuries, but now scientists have uncovered a way to use it to treat obesity.

Dr Robert Molloy from the Department of Health at the University of Leeds and his colleagues said it was possible to increase the amount of fish in your diet by using a blend of fish, flax and sunflower seeds.

“We’re not saying that the amount you take is the same or less,” he said.

“The key is to get the whole fish mix and the whole flax mix, and that’s what you need.”

Dr Molloyle said fish oil was an excellent source of omega-3 fatty acids that have been linked to better cardiovascular health, immune function and weight loss.

“Fish oil is a very important source of these fatty acids, and we’re interested in looking at its effects on fat metabolism,” he added.

He said the main difference between fish oil and saturated fat was the presence of omega 3s, which are considered the “healthy fats” that are important for the health of your heart and your brain.

“There’s also a lot of other things in the diet that may have these omega 3 fats, so it makes sense to look at that, and it does,” he explained.

Dr Mollsoy said he had previously investigated the effects of fish on weight, cholesterol levels, and metabolism, but he was now more interested in how to increase omega 3 intake in the general population.

“When we looked at the effects on obesity, we found that if you added more fish to your diet, it was associated with weight loss,” he continued.

“We found that people who ate more fish had a slightly lower risk of becoming obese.”

Dr James Martin from the University at Adelaide’s School of Health Sciences said it made sense to examine how fish could help people who were obese or were otherwise at risk.

“If you’re eating too much saturated fat, that’s going to increase your risk of developing type 2 diabetes,” he told BBC News.

“That is something that is associated with obesity.”

Dr Martin added that fish oil had the potential to help people with Type 2 diabetes by reducing their risk of complications from the disease.

“A lot of fish oils come from fish that’s been treated with omega-7 fatty acids,” he noted.

This type of fish is found in fresh water, and its omega-6 fatty acids help keep your blood sugar stable.

“As we get into the omega 3 phase, we find that our blood sugar goes down and it becomes more stable, so you need to make sure you’re getting enough omega 3 in your blood to keep it there,” Dr Martin said.

Dr Martin said it might also be possible to find more omega 3 fatty acids in some supplements, like salmon and trout oil.

“In the fish oils, they do have some omega-9 that’s a bit higher in the oils, so there are some fish oils that contain omega-11, but I don’t know what the best amount is,” he remarked.

However, Dr Martin added it was not possible to add too much omega-5 or omega-10 to fish oil, as that would interfere with the absorption of the other omega-4 fatty acids.

Dr George Farrar, professor of nutrition at the Goldsmiths, University of London, said the research was intriguing, but needed more studies to prove the link between omega-III fatty acids and weight.

“It’s not like we’re saying that you need fish oil to be obese, it’s not that fish oils are a great source of the omega-2,” Dr Farrart said.

We do know that omega-8 is better absorbed than omega-1.

But we don’t really know how much of this is going to affect our weight, so we’re trying to get some sort of answer.

If it’s a very high amount of omega 6, you might need to increase that to make up for the fact that it’s higher in omega-13.

“So we need to find out how much we can do to reduce our omega-14 intake,” he concluded.

Follow Alison Smith on Twitter: @alisonsmithbbc