As I mentioned in the post Deciding To Lose Weight – Reflecting On Dietary Habits I’d picked up the habbit of supplementing my healthy lunches with a large amount of crisps. Probably because I like savoury/salty food. However crisps would no longer feature in my new healthy approach to life – they had to go.

It’s not that easy though is it. Lunch just isn’t complete unless you have something else with your drink and sandwhich, so I had to find a replacement for the crisps. The obvious answer, given we’re all continually advised to consume at least 5 portions of fruit and vegetables per day was to substitute either fruit or vegetables for the crisps. So that’s exactly what I did.

It took a while to find something I was happy with. I tried apples, but I seem to have some sort of allergic reaction – annoying as I really like apple. Next I tried raw carrots, but I’m not a big fan of their taste. Bananas are great but I was in danger of eating nothing but bananas (I often had one for breakfast). So finally I settled on grapes. 12 to 20 grapes – depending on whose figures you believe – are a portion, they contain a good range of vitamins and minerals and despite containing a log of sugar aren’t really adding that many calories (around 60kcal per portion).

So that was my next small step on my weight loss journey, eating fruit to lose weight – beats eating crisps anyway!

What is the fat burning zone?

The fat burning zone is the heart rate zone at which you supposedly burn most fat. Typically heart rate zone for fat burning is quoted as being between 60% and 70% of your maximum heart rate. So to work out fat your burning zone you’d calculate you maximum heart rate using the formula: maximum heart rate = 205 – 0.5* your age. The fat burning zone is then between 0.6 * max heart rate and 0.7 * max heart rate. Alternately you can find a few fat burning zone calculators on the web.

The trouble is, fat burning zone is a myth.

Exploring the fat burning zone myth

The concept of the fat burning zone is based on an assumption and some solid science. Firstly the science. It is a fact that at lower intensities our bodies primarily use fat to fuel exercise.  However the fat burning zone makes two assumptions:

1. that the maximum heart rate is the same for everyone of a given age. In reality maximum heart rates vary considerably;
2. that the heart rate measured during exercise can be used to predict the oxygen consumption, which isn’t always true.

So how do we address these assumptions? Well firstly you can actually determine your maximum heart rate on your own using your heart rate monitor.The second assumption doesn’t matter, because the science on which the fat burning zone is based has been misinterpreted.

While it is true that at low intensities your body burns the highest percentage of fat, it does not reflect the best way to burn fat and hence lose weight quickly. Consider this example. Lets assume that you burn 100 kcal per mile  that you run. If you slowly run 4 miles then you’ll burn 400 kcal in theory around 65% of these calories will be fat. Now consider what happens if you doubled you running speed and ran 8 miles in the same time. Now you’ve burned 800 kcal but only 35% of those calories will come from fat. Easy to see why many suggest we focus on low intensity exercise to burn fat.

Lets now consider what that means in terms of calories of fat burnt though. In the first case 65% of 400 kcal is 260 kcal of fat and in the second case 35% of 800 kcal is 280 kcal. So the high intensity exercise burned more calories, more of which came from fat and it has a number of other benefits too (such as even more calories burned as a result of EPOC, but that’s the topic of a future post).

Despite easy access to clean water many of us the live in the west are dehydrated. What we drink does not help either, much of it, for example caffeinated drinks and alcohol has a diuretic effect (dehydrates us and makes us wee more).

Unfortunately our bodies depend on water to function correctly, so when we’re dehydrated our bodies aren’t working as efficiently as they should, which impacts our health and wellbeing. The simple fix is to drink more water and less of the other stuff.

The bonus is that by drinking more water you’re more likely to lose weight – and you’ve not even had to give up your favourite foods to benefit from it!

There are in fact several reasons to drink water to lose weight:

1. our brains often confuse being thirsty with being hungry. So when you feel hungry have a glass of water and wait 20 minutes you might well find you’re no longer hungry.
2. drinking more water (especially cold water) burns additional energy as your body works to maintain it’s internal temperature.
3. water fills up your stomach making you feel fuller.
4. Some scientific studies (for example the one listed below) have shown that drinking around 500ml (two glasses) of water before a meal results in you consuming around 13% less than you otherwise would have.

So how much water should i drink to lose weight? Well it’ll vary from person to person, but you’re almost certainly not drinking enough!

Reference quoted:

Davy BM, Dennis EA, Dengo L, Wilson KL, Davy KP. Water consumption Reduces Energy Intake at a Breakfast Meal in Obese Older Adults. JADA 2008; 108: 1236-1239.