8 min read

Eat Fish, Lose Weight?

Fish is oily.

But in a good way.

You may have heard about these controversial ‘Omega-3‘ fatty acids?

What’s all the hype about?

Well they can probably contribute to:

  • improved cardiovascular function
  • enhanced nervous system function and brain development
  • improved immune health
  • improved blood lipid profile
  • improved memory and concentration

They also show co-relational data to decreased levels of cancer, cardiovascular disease, depression, and potential for stroke.

The benefits of fish oil may include improved cardiac function and reduced internal inflammation though too.

This meta-analysis of 7 controlled, randomized trial studies, showed improvement in cardiac function with fish oil supplementation.

What’s in This Stuff?

Fish Oil is rich in two specific groups of Omega-3 fatty acids — of three that we presently know about, the funny thing about nutritional science is that we’re always discovering new compounds and molecules that make up components of our food, it’s estimated that we know only a small fraction of the compounds that are in our food, and that there may be thousand of compounds we are yet unaware of .

They are known as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA).

DHA and EPA, along with alpha-linolenic acid (ALA), which is found in things like flax, chia, and walnuts, all fall under the subheading of omega-3 fatty acids.

[note]Update September 2012 – Relevent Fact Left out of Original Article: Although those three fatty acids are commonly accepted as the three MAIN forms of essential Omega-3 fatty acids for human consumption, there are in fact, at least 11 different Omega-3 fatty acids. 

There is increasing evidence to suggest that Docosapentaenoic Acid (DPA) is a missing ‘fourth’ Omega-3 from my list, and that arctic fish, may offer health benefits as well.

Further evidence to suggest that what we currently know about nutrition is ever-evolving, and we tend to think we know about nutrition than we actually do. [/note]

ALA is however typically observed as significantly less potent and therefore less usable by humans because it must be converted to DHA/EPA by the human body.

Fish probably get most of their EPA and DHA from algae, which is the base of the food chain for fish and so algae, spirulina, kelp, nori, etc… may also be good things for you to be eating.

Bored Yet?

Why Omega-3’s?

Aside from all the potential health upside from above, the reason supplements with Omega-3’s has become a highly recommended supplementation strategy is because they have been disappearing from our food chain and the oils found in wild fish are perhaps the most pure source that is bioavailable for human absorption.

Mostly because wild fish themselves are relatively the same as they were a hundred years ago, only our fishing methods have changed.

As we feed animals — particularly ruminants (cows, deer, bison, etc…) who are herbivore’s and need to eat, then convert grass into muscle mass — a diet increasingly higher in corn and other grains, we’ve effectively tainted the food chain, at least the North American one.

The saturated fat ‘evil-craze,‘ had a little to do with this too, as we shifted a lot of our fat consumption off grass-fed butter in favour of peanut or canola oil instead, we’ve only increased our consumption of Omega-6 fatty acids (another poly-unsaturated fat) when in reality, the problems with any one fat, might be over-consumption out of balance.

There are at least ten Omega-6 fatty acids, but not all are considered ‘essential.’

By some estimates we now consume about 20:1 Omega-6 to Omega-3, when our ancestors were probably closer to 1:1 ratio.

Other evidence suggests there are health concerns when this ratio exceeds 4:1 (O-6 : O-3) — so a 3:1 ratio or less seems ideal…

This suggests we all probably need to increase our intake of Omega-3’s to offset our dramatic increase in consumption of Omega-6, and/or simply decrease the amount of Omega-6 fatty acids we’re consuming.

It might not even be that Omega-3’s themselves are that healthy for us, but the research could be indicating that by displacing other worse things for us — like a diet high in processed grains — we can effectively improve our health and our waist lines.

One final note on this out of whack ratio is that — like many of us have, the Canadian Food Guide listed 10-12 servings of grains per day as ideal when I started training in 2004 — it has been linked with metabolic damage and inflammation, meaning it could possibly prevent us from achieving a healthy weight, which is where fish consumption or fish oil supplementation may come in for you.

Fish (Oil) and Weight Loss

Hopefully, what we’ve seen is that omega-3 consumption may contribute to many health benefits, but specifically regarding weight loss, the research is a mixed bag.

I’ve not found enough research that would conclusively suggest that it aids in weight loss, particularly in countries where high levels of fish consumption are the norm or the food-chain is less tainted.

Most research also is geared towards health conditions and it’s use as a supplement in things like heart disease, cancer, diabetes, etc…

However, anecdotally I can tell you that in some cases brief periods of fish oil supplementation has been associated with positive benefits in my weight loss clients, particularly in the first 6 months.

My assumptions about this?

First, it probably offsets their omega-6 consumption and balances out their fatty acid profile internally.

Then, if I had to guess, I would say that Omega-3 supplementation leads to a lot of other health benefits, which in turn generally creates a cascade effect; This makes people feel better, and thus more capable of exercising harder but also more alert/conscious of the other foods they are consuming.

My Recommendations

I’ll use supplementation strategies with fish oil only when dealing with someone new to me, whose diet I know to be high in Omega-6’s presently.

*Unless they are on a blood-thinning agent, in which case fish oil supplementation should be AVOIDED.*

Typically 5 grams, or about 1 tsp daily for the first 3-6 months — I prefer liquid flavoured variations like this one over capsules.

However, I favour whole food options whenever and where-ever possible and would rather simply coach people on removing/lowering certain things from their diet and increasing their consumption of other things.

So if you eat a lot of the following and are starting a ‘weight loss program,’ you may consider supplementation while you gradually reduce your consumption of some of these foods:

  1. Grapeseed Oil
  2. Corn Oil
  3. Walnut Oil
  4. Cottonseed Oil
  5. Soybean Oil
  6. Safflower Oil
  7. Margerine
  8. Peanut Butter (and some other nut butters)
  9. Processed Foods…

That list is by no means exhaustive, but what you generally tend to find is that seed, nut and grain oils are the worst offenders.

Processed foods is also where many of those ingredients find their way, in large quantities too.
Cut out the consumption of heavily processed food and work towards changing your cooking oils to coconut, olive, macademia nut, (high in mono-unsaturated fat like olive, low in omega-6), avocado oil, and preferably grass-fed rendered lard or butter instead.

It’s important to note that Omega-6’s are still considered essential fats; For example they play an important role in promoting cell health, so the trick with diet here, is to establish balance by lowering their consumption via mostly processed foods, but not to exclude them entirely — not that you really could…


An essential fat basically means that we can’t make omega-3 and omega-6 fatty acids in our bodies, so we need to get them from our diets.

I recommend getting them in your diet with either whole nuts, grains, and seeds, or small amounts of nut or seed butters — one tablespoon is a serving of peanut butter, whereas a handful (1/4 cup) of peanuts is considered one serving, this is important to keep in mind.

The occasional use of one of these oils most likely wouldn’t hurt either, just do it every once and a while; After all, a lot of Asian cuisine just wouldn’t be the same without a little sesame oil.

Also corn in it’s whole form is only about 4-5% Omega 6, while when found in oil form that ratio shoots up to over 50%, so the ‘type’ of food is important to consider as well.

I’m not saying grains, nuts or seeds are bad for the record, just ideally eaten whole, rather than in processed foods or as oils.

After you’ve reduced the worst Omega-6 offenders, you’ll likely want to work towards increasing your consumption of these foods to at least two servings per week but not necessarily more than four (emphasis on the seafood and algae):
  1. Salmon
  2. Mackerel
  3. Sardines
  4. Cod (I especially like black cod, also called Sablefish)
  5. Halibut
  6. Tuna
  7. Shrimp
  8. Scallops
  9. Pasture-Raised Meat (Bison, Beef, Wild-Game, etc…) and Eggs (or Omega-3 Eggs…)
  10. Dairy (Omega-3 Enriched, or coming from Pasture Raised Animals)
  11. Kelp/Algae (Sushi anybody?)
  12. Chia (whole, preferably not butter or oil)
  13. Flax (whole, preferably not butter or oil)
  14. Walnuts (whole, preferably not butter or oil)
  15. Edamame (whole soy beans, unprocessed)
  16. Wild Rice (not regular rice, which is a grain)
  17. Dark Leafy Greens (Spinach, Grape leaves, Broccoli, etc…)

Ultimately it’s important to have a varied diet; While many of the best omega-3 sources are meat oriented, there are some seeds like flax or chia that are particularly high in ALA — remember the not-so-well-absorbed type of Omega-3 from above? — and many other good vegetable options, that have higher amounts of Omega-3’s relative to Omega-6 if you’re a plant-based eater.


When I do go with a supplementation recommendation, it’s usually for the health benefits, and not particularly for weight loss.

If it is for weight loss purposes and I’m going through the recommendation process above, then I’ll typically wean people off any supplementation with fish oil after 3-6 months, for three reasons:

  1. Excessive consumption of any particularly food/nutrient is most likely not good, it has been associated with allergy development and other health concerns.
  2. A better diet should create the right balance after 3-6 months of coaching, allowing us to move on to other topics of change.
  3. Diets should be somewhat cyclical in nature, and historically has been seasonal for us, there is definitely something to a pattern of seasonal eating.

The Short Version

1. Increase the consumption of seafood to at least twice a week, if meat is permissible in your diet. Opt for regular algae, dark leafy greens and potentially chia & flax consumption if you’re a plant-based eater.

2. Try to transition your meat consumption to pasture-raised, grass-fed animals; likewise for dairy or eggs.

3. Utilize some Omega-3 fortified foods if you like. 7 Omega-3 eggs is roughly the equivalent of 1 serving of fish (4 oz).

4. Supplement if you want for 3-6 month periods, but recognize that taking fish oil (or algae oil) is probably more associated with positive health benefits than specific to weight loss. Those benefits may be negated if you already have a lower consumption of omega-6’s, and a higher consumption omega-3 foods like fish, algae, and grass-fed pasture raised animal products in a ratio of 3:1 or lower (omega-6 to omega-3).

5. Do NOT use fish oil supplementation if you are on a blood-thinning agent.