make a semi-solid (i.e. margarine), which has a longer shelf life. TFAs are thought to have many
negative health consequences and their intake should be minimized. An emphasis on
unprocessed foods will minimize the intake of TFAs.
Little research has examined the effects of different types of TG on a ketogenic diet,
although one study suggested a difference in weight loss and thermogenesis between olive and
corn oil, with corn oil being the preferred choice (13). Anecdotally, many individuals find that
increased intake of unsaturated fats, especially flax oil, tend to increase fat loss compared to a
high intake of saturated fats. As well, many individuals who have found that their blood
cholesterol levels increase on a ketogenic diet note that cholesterol decreases if more unsaturated
fats are consumed.
To minimize potential health problems, consuming primarily unsaturated fats may be
ideal. However, avoiding all saturated fats would be unrealistic since this will further limit the
number of foods available to ketogenic dieters. In practice, most individuals will end up
consuming a mix of both saturated and unsaturated fats during the day. A source of EFAs, such
as flax or safflower oil, should be consumed. Alternately some individuals have consumed foods
such as flax seeds or flax meal or consumed fatty nuts to fulfill their EFAs requirements.
Timing of fat intake
As with protein intake, there is no specific time to consume or not consume dietary fat on
a SKD. Most individuals tend to spread dietary fat more or less evenly throughout the day, if for
no other reason than to avoid stomach upset. The exception is immediately after a workout
when dietary fat is not desirable, as it will slow digestion of post-workout protein intake.
Summary
With the exception of the small requirement for the EFAs, there is no essential reason to
consume dietary fat as ketosis can readily be induced with a diet of all protein and a small
amount of carbohydrate. However, to avoid metabolic slowdown from an excessively low caloric
intake, dietary fat is necessary as a caloric ballast since protein and carbohydrates must be kept
relatively static on a ketogenic diet. From a purely practical standpoint, dietary fat provides
fullness and taste as a diet of pure protein is monotonously bland.
While little research has examined the optimal type of fats to consume on a SKD, when
possible it is beneficial to consume more unsaturated vegetable fats over saturated animal fats
to avoid any potential problems with blood lipid levels. To avoid all saturated fats is nearly
impossible considering the generally high intake of animal products on a ketogenic diet.
Timing of fat intake is not critical to success of the diet. The exception is that dietary fat
should be avoided post workout so that protein ingested at this time can enter the bloodstream
quickly to help with post-workout recovery.
Section 5: Other dietary effects on ketosis