Can you just leave the diet as it is, and train your way into great shape and lose fat? There is some great research on this, and the answer is a pretty firm ‘no’. Can you lose fat just by upping the ‘calories out’ – your exercise? Exercise actually has a fairly limited and sometimes not noticeable effect on weight loss. Ideally, diet is the primary thing to change, and exercise plays an auxiliary role. Not to say though, that being fit and active is not independently good for you. It’s one of the most important things you can do for your health. Fitness is medicine.


If you are physically active, you’re going to live a good, long, healthy life. You’re going to feel better and be more awesome at just about everything.


Exercise and fitness can play an auxiliary role in managing your health, particularly looking at weight loss.

When we talk about weight loss, we think about ‘calories in and calories out’ as being an old model that’s much too simple to understand the metabolic complexity of being a human and the feedback systems that exist around hormones, particularly insulin.

  • Being physically active and fit by exercising really improves insulin-sensitivity.

That’s an important thing, because the more insulin-sensitive you are, the more easily you’ll manipulate insulin down and get the normal homeostasis of being in good shape working.

You’ll still have to change your diet. You can’t continue to eat the ‘Standard American Diet’ – refined processed food, particularly carbs and sugar. You’ll have to change your diet, but it could be more effective the more insulin-sensitive you become.

There are a couple of other auxiliary roles that exercise might play.

  • You’re probably going to drive muscle mass, which is a metabolically active organ, that in itself makes you more insulin-sensitive.
  • This is an overlooked one, I think –  being fit and active, particularly outdoors, drives brain-derived neurotrophic growth factor (BDNF) and frontal cortex development. This is an important part of the brain, because it controls what you will and won’t do. It controls your planning, and a whole lot of stuff to do with overall cognition. More importantly, that’s some of your willpower – will I say no to this treat or will I say yes?

There are also some other psychological benefits from being fit and putting some effort into your health, in terms of weight loss. You’ve got some skin in the game. “I’ve tried this hard, I’ve already been doing this today, therefore I’m not going to do these other poor behaviours.”



Grant’s Top-5 Exercise and Weight Loss Tips

1. Fat-burning exercise

Do some easy, fasted exercise, particularly first thing in the morning. This is easy endurance work, such as walking or cycling. Some of you will be fit enough to run. But keep an eye on that intensity. I use Phil Maffetone’s Maximum Aerobic Function (MAF). Just when you start to huff and puff, you need to slow down. This is easy work that you could continue for a very long time. If you do that fasted and you’re doing it easy enough, then you’re going to drive autophagy – cellular clean up. You’re going to drive insulin and glucose down. It’s a profoundly anti-inflammatory, ketone-producing state. I even call it ‘fasting mimicking exercise’ or FME.

This is a great place to start. The trick with it, of course, before you walk out the door that morning, particularly if you’re going out with other people, is you need to get your ego, take it out of your head, put it in a brown paper bag and leave it on the kitchen counter. Because you’ll end up going very slowly. People who look in much worse shape than you will overtake you. And that’s okay. This is easy, ego-less exercise.

2. Avoid the grey zone

Avoid what I call the metabolic grey zone, which is that zone just above that easy aerobic training. I see most people exercising in that zone. You’re burning primarily carbohydrate as fuel, not fat as in the fasting mimicking zone. You’re not enhancing your fat burning. You’re making reactive oxygen species. You’re providing an inflammatory environment. And I think that elevates cortisol.

A lot of people just train harder when they’re not losing weight. They end up in that grey zone doing more damage and getting fatigued.

3. Do the hard stuff

If you do some hard exercise, which, if you’re up to it, you should do now and then, do it only briefly and make sure you go hard enough. To give you an example, yesterday I did some short sets of sprints on the beach, followed by five flights of some very steep steps that took about a minute to run up. It was really hard, but it was really short. So, I’m polarising between those.

4. Do some strength exercise

It doesn’t have to be in a gym. You can do some push-ups, pull-ups, some squats with a bag on your back or something similar to get those big muscle groups, upper and lower body, working. You should have a range of movement in that, that can lead into some of that strength training. It can also be mobility training.

5. Enjoy it!

If you’re not enjoying it, change to something else, do something that you do enjoy. Exercise should be fun. For me, that’s most often outdoors with other people, with the dog, in the fresh air, hopefully by the sea or in the forest. I’ve taken up mountain biking recently and that’s a bit of fun. I’m not very good on the downhills, so there’s something to work on.


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