Does Fish Oil Help You Lose Weight?

Does Fish Oil Help You Lose Weight?

9 minute read

Omega-3 supplements like fish oil are among some of the most popular nutrition supplements, and for good reason. These healthy fats are well-known to have a wide array of potential health benefits, from supporting your heart health to your brain development. They're especially good when paired with other healthy lifestyle habits.

Fish oil is sometimes cited as a tool for losing weight and managing body composition. So it's only natural to be curious whether fish oil can help you lose weight. 

Here's what you should know about fish oil and weight loss and how you can properly use Omega-3s to reach your fitness and body composition goals. 

What is fish oil?

What is fish oil

Fish oil is a popular dietary supplement. As the name suggests, fish oil is extracted from fatty, cold-water fish. The oil is then processed into either capsules or a liquid oil which you can add to your daily dietary regimen. 

The big reason that fish oil is so popular is that it is one of the best-known sources of omega-3 fatty acids. Omega-3s are a classification of healthy fatty acids that are often taken for heart and brain support*. Your body can't make omega-3s on its own, so you need to get them from dietary sources.  

Fish and fish oil are particularly valuable as omega-3 sources because they contain both EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). While there are many kinds of omega-3s you can find in different foods and dietary supplements, DHA and EPA are especially valuable for your health because of the various roles they play in fetal development, cardiovascular health, immune function, and brain health.*

Does fish oil help you lose weight?

Does fish oil help you lose weight

Weight loss is an extremely hot topic in today’s healthcare priorities. With almost half of American adults reported to be obese, and many of our most pressing health concerns linked to elevated BMI (body mass index), it's no secret that the prevalence of obesity has major repercussions down the line. 

So it’s no wonder that the use of fish oil for weight loss is gaining some attention in this realm as well. After all, omega-3s have been shown to play roles in many different health aspects, and many of those (like heart health) have direct ties with body weight. But do fish oil supplements actually help you lose weight?

In short: they might. 

The bottom line is that weight loss is a complex undertaking that depends on various factors, one of the most important of which is the number of calories you eat versus the number of calories you burn. Significant weight loss usually requires a consistent commitment to healthier lifestyle changes like choosing healthy, properly-portioned foods and increasing physical activity to achieve long-term success.

To be completely clear, it's important to understand that you shouldn't depend on omega-3 supplements to help you manage your weight. There usually are no dependable shortcuts, including omega-3 supplements. Even though some evidence suggests that omega-3 supplements can positively affect people trying to lose weight, these studies are generally small or inconclusive, and more research needs to be done. Instead, look at it this way: adding omega-3 supplements may help some populations manage their weight more successfully.

However, with that said, there is evidence that adding an omega-3 supplement into your routine can help manage some of the metabolic actions that your body needs to get to a healthy weight. For example, some research suggests that omega-3 supplements can aid in managing your appetite, improving your body composition, and speeding up your metabolism.

Appetite management

Appetite management

One key way that a fish oil pill may help you manage your weight is through appetite suppression.

Because your weight is heavily influenced by the number of calories you eat in a day versus the number you "burn" for energy, overeating is a major roadblock for weight loss. But fish oil supplements may help curb appetite in some groups, which can have a positive ripple effect on your weight management efforts. For example, a 2008 study found that omega-3 supplementation in overweight and obese adults following a calorie-restricted diet was linked to lowered reports of hunger and appetite after dinner compared to those who weren't taking the supplements.

However, it's important to note that another study found that fish oil supplementation actually increased appetite in healthy adults. Another study showed that short-term omega-3 supplementation in young male athletes also increased appetite and sweet/carbohydrate cravings. Again, these contradicting points of evidence are more good reasons to remember that you shouldn’t depend on fish oil alone for weight loss, and that individual nutrition needs can vary widely depending on your current weight and health status. 

Improving body composition

Improving body composition

Omega-3 fatty acid supplementation may also positively affect another factor that isn't specifically related to weight itself but is just as important: your body composition. 

There is evidence that omega-3 supplementation may be linked to increased lean muscle mass and decreased body fat percentage, even if total body mass does not change significantly.  

Another meta-analysis that evaluated 21 different studies had a similar finding: even though these studies didn’t show that fish oil supplementation was effective at reducing body weight or BMI, there was enough evidence to suggest that it was helpful at reducing abdominal fat, waist circumference measurements, and, as a result, waist-hip ratio when combined with other healthy lifestyle changes. Because your waist-hip ratio is another important consideration besides BMI used to evaluate body composition, this could be a promising discovery even if body weight itself doesn’t change! 

Speeding up metabolism

Speeding up metabolism

If you've blamed your weight woes on a slow metabolism, fish oil or other omega-3 supplements might help here.

Metabolism is the speed at which your body uses calories for energy. The faster your metabolism is, the more calories you burn at a given time. This can ultimately translate to weight loss, especially when combined with healthy habits like calorie-controlled dieting and regular exercise. 

Your metabolism is based on a variety of factors, especially your genetics. However, there is some evidence that omega-3 fatty acid supplementation can help increase metabolic rates. For example, a small study found that fish oil supplementation was associated with a 14% increase in resting metabolic rate and a 10% increase in energy expenditure during exercise in healthy older female subjects.

How much fish oil should you take?

How much fish oil should you take

The amount of fish oil you should take can vary from person to person. There is currently not enough evidence for an official recommended intake of omega-3s. However, as a general rule, it's recommended that men have 1.6 grams of omega-3s per day, while non-pregnant/nursing women get 1.1 grams of omega-3s to meet the adequate intake.

However, this can also change based on your specific health needs. For example, the American Heart Association recommends 1 gram of EPA+DHA for people with cardiovascular concerns. Pregnant women are generally recommended to get about 200 mg of DHA for adequate fetal development support.

More pertinently, there is no recommended omega-3 dosage for weight loss, and the amounts used in studies to evaluate their effect vary widely. If you decide to take an omega-3 supplement for weight loss or any other reason, check in with your doctor first to determine the correct dosage for your needs.

Sources of omega-3s

Sources of omega-3s

As we've already covered, two of the most important omega-3s that you should be looking for are DHA and EPA. Some of the best-known sources for these two specific omega-3s are fatty, oily fish found in cold water environments like salmon, mackerel, and tuna. The American Heart Association even recommends eating two servings of fish (especially these fatty fish) because of their valuable, healthy fat stores. 

However, many people don't eat enough fish regularly to reap the benefits. A more convenient option is fish oil supplements, which are available in supplement form to make it easier to get those omega-3s. 

Sources of plant-based omega 3s/supplementation 

Sources of plant-based omega 3s/supplementation

But what if you want to get omega-3s but are following a plant-based diet, or if you can’t eat fish for other reasons? In cases like these, you can get omega-3s from plant sources!

Many plant-based omega-3s come in a different form than EPA and DHA. Instead, you’re more likely to find ALA (alpha-linolenic acid). This type of omega-3 is found in a couple of different vegan-friendly food sources including: 

  • Chia seeds
  • Hemp seeds
  • Flax seeds
  • Walnuts
  • Kale
  • Brussels sprouts

Unfortunately, your body needs to convert ALA to EPA and DHA to use this omega-3, and the conversion process is not very efficient. 

So the best source for plant-based omega-3s is a somewhat unlikely origin: microalgae! 

Algae oil pills, like fish oil pills, are made from marine sources and are an excellent alternative for anyone who doesn't eat fish since it's made from aquatic plants rather than animals. Even better, unlike other plant-based omega-3salgae oil pills contain both EPA and DHA, which means you can directly get all of your most important omega-3s without compromising dietary restrictions.


Omega-3 supplements are highly helpful supplements for a variety of health-supporting reasons, and there is more and more evidence that they may play a role in helping you manage your weight. While it's still too soon to conclusively say that fish oil can help you lose weight, taking omega-3 supplements have been linked to appetite suppression, improved metabolism, and body composition, all of which may help you manage your weight when paired with other dietary and lifestyle interventions.

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