Are Low Fat Foods Making Us Fat?

Hey kids, it's Crabby!  Who is once again not posting while on vacation. So yes, this is a guest post, as you can tell by the fact that there is actual nutrition research involved. If I'd written it, there'd just be a bit of nagging about not trusting slick advertising campaigns, followed by some whining about the lack of healthy convenience foods for lazy people, and then perhaps some gratuitous pictures swiped from icanhascheezburger.

(Photo credit:

Whoops, sorry--not sure how THAT got in there!

So thank goodness this post is by Brendan Wilde, who is a health and wellbeing writer over at and the UK National Register of Personal Trainers (where you can learn more about personal trainer courses if you're so inclined). While he does the hard work of explaining the metabolic implications of various dietary variables and particularly the impact on insulin resistance and weight gain, the Crab and Lobster will be kicking back enjoying their final days in Scotland.  Which, as it turns out, has a more incredible scenery than any human can absorb without exploding, plus many delightful ways to screw up your metabolism six ways from Sunday.  Um, unless beer and shortbread cookies have been declared health foods in my absence?

Anyway, I'll shut up now.  Take it away, Brendan! 

Is the low fat food fad all it is cracked up to be?

Do reduced-fat foods help us lose weight? Or could they actually be contributing the rise in obesity?

Processed foods may well be low in fat, but we all know that does not mean they are low in calories.

In fact many low fat foods have just as many calories as their full fat counterparts. And furthermore, many low fat foods are ‘adulterated’ with additional, high glycaemic carbohydrates, to improve the taste. Especially popular and troublesome is the controversial sweetener high fructose corn syrup.

The importance of Dietary Fats for General Health

Dietary fats are essential to our overall health and wellbeing. They help us absorb fat soluble vitamins A, E and K; they serve as a reservoir for energy storage; and they are needed for the healthy function of our brain, nervous, immune and hormonal systems.

They are also essential for helping maintain a normal metabolism which controls how quickly our body burns energy. Severely limiting fat intake will slow down our metabolic rate, meaning we need fewer calories initially, but also meaning that we gain weight quickly as soon as extra calories are added.

Fat, Insulin and blood sugar

Then we need to add the hormone insulin into the equation, which has everything to do with fat storage and weight-gain. Insulin is the hormone responsible for regulating our sugar levels by moving sugar out of the bloodstream and into our cells. The body first converts this sugar into glycogen, which is stored in the liver and muscles. When they are full, the remaining glucose is stored as body fat.

However, it is vitally important to understand that insulin – and subsequent fat storage – behaves differently, depending on the types of food eaten. Carbohydrates especially are high-GI carbs such as the sweeteners added to many low-fat foods, stimulated the greatest insulin response. Fats, on the other hand, do not raise insulin or blood glucose levels.

When insulin is circulating in the bloodstream, even at quite low levels, fatty acid synthesis is activated, and the burning of stored fat is greatly inhibited. Insulin prevents your body from making the hormone-sensitive fat-burning enzyme, lipase. Essentially, this means that your fat-reduced processed foods, with added carbohydrates, force your body into making fats, not burning them!

When you eat a low-fat, high-carb food, your blood glucose level will be back down to normal after about 90 minutes, but your insulin levels will still be high, working to stack glucose away in your fat cells. This often leads to a blood sugar slump, which comes with an overwhelming desire to reach for the next carbohydrate fix… often in the shape of a chocolate biscuit or a slice of cake. And so the whole cycle begins again. Hunger is ever-present and along with it comes gradual weight gain.

Repeated for long enough, this cycle of insulin elevation can lead to insulin resistance, whereby ever higher levels of insulin are needed to move blood sugar across the cell membranes, More insulin means more fat deposition, and this is a precursor to the development of Type ll diabetes.

Ironically, the most comfortable and effective way to lower insulin levels, and encourage the body to burn stored fat instead of blood glucose, is to limit carbohydrates, while making sure that you are taking in adequate levels of healthy dietary fats.

This forces the body to burn fat for fuel, without any of the feelings of starvation inherent in low-fat, low calorie dieting.

So, how do you regulate insulin levels and encourage your body to burn fat? Not by becoming a low-fat junkie! Exercise regularly, using a combination of aerobic activity and resistance training to build lean muscle, in order to increase your resting metabolic rate. Eat five or six mini-meals a day, made up of low-glycaemic index carbohydrates (vegetables or fruit), healthy fats and proteins. And avoid the high glycaemic index carbohydrates frequently found in processed food as a result of added sweeteners such as high fructose corn syrup.

What do you folks think about "low fat" foods, do you grab 'em up or take a more skeptical approach?

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