Can Fish Oil Help You Lose Weight? (Recommended Dose)

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This article has been Fact-Checked by Kendall Kennedy MS, RD, RYT

There are many substances that supposedly help you lose weight. Some work, others don’t. Can fish oil help you lose weight?

Fish oil is a popular supplement because of the variety of possible health benefits. Find out if weight loss is one of the benefits you can expect.

What exactly is fish oil?

Not all fats are the same. Within the category fats you have omega-3 fats, commonly found in foods like fish and flax seeds. Within the category omega-3 fats you also have different fatty acids. The 3 main ones are ALA, DHA, and EPA.

Fish oil is a combination of omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid).

One of the most common ways to conume fish oil is in capsules.

Different brands of fish oil contain different EPA-DHA ratios. Often other substances like for example vitamins are present too.

Fish oil can improve weight loss from exercise

Fish oil can possibly improve exercise performance which would lead to more calories burned (1). One study found improvements in metabolic rate and fat oxidation at rest and during exercise because of fish oil (2).

Another study also found that there might be a synergistic relation between exercise and fish oil. That means that the two together can provide more benefits than either alone (3).

There are however also studies that don’t reach the same conclusion (4). All in all it’s too early to make any strong conclusions about the effectiveness of fish oil in this area.

Fish oil can increase your metabolism

Another theory is that fish oil can increase the amount of calories you burn every day (2, 5, 6, 7).

Again the findings are not the same over all different studies on the subject (8).

Fish oil can improve body composition

One thing that most studies agree on is that fish oil can improve body composition.

Fat loss doesn’t always result in weight loss and vice versa. You can for example gain the same weight in muscle as you lose in fat. This would be beneficial for your health and long-term weight loss but right now it can feel like you’re not making any progress.

Body composition, your fat-muscle ratio, is important too. Fish oil may help you achieve a healthier body composition.

There are multiple studies that don’t find an immediate improvement in weight but they do find an improvement in body composition (6, 8, 9, 10).

One study found a decrease in liver fat (11). Fish oil can also slow down the decrease in muscle mass in older individuals (12).

Since muscle mass burns slightly more calories than fat mass these changes in body composition should result in a slight increase in weight loss in the long-term.

Fish oil can improve body composition

Fish oil compared to fish

In general it’s better for your health to get your nutrients from whole foods instead of supplements. Find out how much fish is the same as fish oil in terms of EPA and DHA content.

A fish oil capsule of 1 gram is not necessarily pure omega-3 fatty acids. The amounts vary from brand to brand but let’s take a 2000 mg capsule with 400 mg DHA and 600 mg EPA as an example.

Here are how much DHA and EPA fatty acids certain food sources contain (13):

  • Salmon, Atlantic, farmed cooked, 3 ounces: 1240 mg DHA and 590 mg EPA
  • Herring, Atlantic, cooked, 3 ounces: 940 mg DHA and 770 mg EPA
  • Mackerel, Atlantic, cooked, 3 ounces: 590 mg DHA and 430 mg EPA
  • Trout, rainbow, wild, cooked, 3 ounces: 440 mg DHA and 400 mg EPA

If you’re purely looking at DHA and EPA intake, fish oil capsules can be an easier way to get bigger amounts.

The protein and calorie you get from fish can be really helpful for weight loss. That being said, it’s unlikely that someone eats fish every day.

Recommended daily dose

It’s important to take a closer look at the fish oil you want to supplement with. You might consume the right amount of DHA and EPA but consume too much vitamin A at the same time.

Fish oil supplementation can also cause blood thinning. It’s also smart to talk to a doctor before consuming fish oil if you take any medication.

The FDA recommends a maximum of 3000 mg a day for DHA and EPA combined (14).

Should you take fish oil to lose weight?

Fish oil will likely help you lose some weight but it’s not clear in what extent. Regular fish can be a great weight loss food as well.

The amount of extra calorie burning will most likely not come down to 100’s of calories a day. In the worst-case scenario a good fish oil supplement will only provide you with other health benefits.

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Matt Claes founded Weight Loss Made Practical to help people get in shape and stay there after losing 37 pounds and learning the best of the best about weight loss, health, and longevity for over 4 years. Over these years he has become an expert in nutrition, exercise, and other physical health aspects.