Can you Eat to Boost your Metabolism?

Ever wonder why some guys eat almost anything yet never put on weight, while you check food labels for low-fat stuff, deprive yourself of burger rolls and beer, but just can't budge that spare tire? Perhaps you eat more than you think you do. Or maybe all you need is to walk, tap your toes, swing a racket, chase a ball, clean out your garage or lift some weights to build muscle and boost your metabolism.

This is how your metabolism works: all the food you eat is converted into energy. The term 'metabolism' refers to the way your body processes carbohydrates, proteins and fats to release the energy it needs for various processes. Your metabolic rate is the speed at which this energy release occurs.

Is it true to say that some people have a naturally high metabolism rate? Not really. Over nearly 20 years of research, the Medical Research Council Nutrition Unit at Cambridge, in the UK, never found anyone who had a 'slow' metabolic rate. In fact, their studies show that lean and obese men burn exactly the same number of kilojoules per kilogram of body weight. In other words, obese guys actually burn more kilojoules in a day than leaner guys with the same activity pattern. The simple fact is that people who eat less are thinner than those who eat more.

Your metabolic rate is the sum total of three types of metabolism: your basal metabolic rate (BMR), your physical activity energy expenditure (PAEE) and the thermic effect of food (TEF).

BMR is the amount of energy you need to support basic body functions, even if you lie watching TV all day. It accounts for 60 to 65 percent of the kilojoules (kJ) you eat daily. About 25 percent of the kilojoules you eat goes to the physical activity you expend above your BMR. This is your PAEE, and it varies according to how much you move in the course of the day. So it would be high on the day you run a marathon, but quite low the next day, when you veg out and recover.

About 10 percent of the kilojoules you eat is used to fuel the process of digesting, absorbing and storing. This is the TEF. So if you eat 12 000kJ a day, you burn 1 200kJ simply chewing and digesting.

The TEF accounts for 10 percent of your metabolism rate, but don't go thinking you can eat more to lose weight. The average TEF is only equivalent to about two slices of bread and honey, without butter or marge. Despite what some people think, you can't increase the TEF significantly by eating certain types of food. Even caffeine causes such a small rise in the metabolic rate that it has no effect on weight loss or gain.

Some research claims you can increase your TEF by replacing some refined, high-glycaemic-index (GI) carbohydrates, like bread and potatoes, with lean protein in a meal. Even if protein does increase the TEF, this is such a tiny percentage of your total daily energy expenditure that it can't make you lose weight.

Your metabolic rate dictates how many kilo-joules you burn and is determined by your age, weight, height, gender, state of health and activity level. You can't control genetics or age, but you can change your diet and activity levels.

As a rule, if you eat the exact number of kilojoules you expend when you combine your BMR, TAEE and TEF, your weight will remain constant. To lose weight, then, you either have to reduce the number of kilojoules you take in, or increase the number of kilojoules you expend on physical activity.

Ideally, you would do both. To illustrate: An average 70kg male who runs slowly for 60 minutes expends approximately 2 500 to 3 000kJ of energy. Since there are 38 000k J in a kilogram of fat, he'd need to do about 15 hours of extra exercise per week to lose one kilogram of fat. Clearly, it's difficult to lose excess weight by exercising alone. You need to reduce your kilojoule intake as well.

So isn't there anything you can do to hurry things along by boosting your metabolic rate? Sure there is. These metabolism boosters can help you along, but ultimately, when it comes to weight management, there is no substitute for eating less and moving more in a sustained, ongoing fashion. That said, read on...

You've heard it before, a million times. But when it comes to optimizing your metabolism, what does it really mean to ‘eat sensibly’?

1. Maintain your balance. Make sure your diet contains the correct balance of protein and carbs. Fifteen to 20 percent of your kilojoules should come from protein (make sure they're low-fat sources, like skinless chicken, skim milk or low-fat yoghurt), while around 55 percent should come from carbohydrates (again, low-fat options like rye bread, lentils, chickpeas or baked beans are preferable to high-fat carbs like croissants or bagels).

As a rule, keep fat intake low because any excess will increase your body fat. Studies show that the body uses a lot less energy to store fat than it does to store excess proteins and carbs, which require more energy to be converted into fat.

Avoid butter, margarine, chicken skin and visible fat on meat. Keep your fat intake low while still making sure that 20 to 30 percent of your daily kilojoules comes from unsaturated fats like sunflower and olive oils, fatty fish (salmon, sardines, pilchards), avocadoes, nuts and seeds.

2. Eat little, more often. Aim to eat three to five small meals containing low-GI carbs throughout the day to keep your blood sugar stable and provide a steady source of energy to fuel your metabolism. Any excess kilo-joules you take in during large, bulky meals will only get stored as fat.

3. Don't skip breakfast. If you do, your body will think it's starving - it's had nothing for eight to 10 hours - which means your blood sugar will plummet, making it more likely that you will overeat at lunch or supper. Which brings us to the next point...

4. Don't starve yourself. Dropping your kilojoule intake to less than 6 000kj a day will signal to your body that you're in starvation mode, which will temporarily slow down your metabolism. If you fast for 24 hours, your daily energy expenditure will decrease very quickly. The good news: This is temporary. When you start to eat again, it will come back up.

There's no permanent damage to your metabolic rate. But neither is there any benefit to sacrificing yourself at the altar of nutritional deprivation.

5. Don't shovel it in at dinner. Make the last meal of the day your lightest. Depending on your weight and age, your body burns a specific number of kilojoules per kilogram per hour while you're sleeping. If you take in 2 500kJ or less at dinner, there's enough time to use up all the kilojoules while you sleep. However, a 5 000kJ dinner may mean the kilojoules that are left over will go to your fat stores.

6. Drink like a fish. Dehydration can contribute to an inefficient metabolism and cause fatigue. When you're dehydrated, your body's ability to convert carbohydrates into energy plummets. If you exercise regularly, you need to take in around 30ml of water for every kilogram you weigh. So if you weigh 70kg, you need a minimum of 2.1 liters of fluid daily. At least 1.5 liters of this should be water. High-GI drinks (see below) should make up the balance during and immediately after exercise. Low-GI drinks are suitable before a. workout.

Remember to weigh yourself before and after a strenuous exercise session. If your weight changes by more than 0.5kg, then you need to drink more during exercise.

You could try boosting your PAEE through aerobic exercise, which increases your heart rate and can raise your metabolic rate while you’re working out (and possibly some hours after), but those extra kilojoules spent are a small percentage of the total energy expended in a day, and not enough to allow for an extra beer.

What kind of exercise are we talking about? It depends on your starting point. Linear-pattern cardiovascular training (cycling, running, swimming) can be an effective initial weight-loss strategy in an untrained person. The problem is, your body adapts to training in about three months, becoming more efficient at utilizing smaller amounts of fuel for the duration of the workout.

A better idea: cardio workouts that engage the nervous system, and thus the brain. These are more effective as weight-loss aids (than linear-pattern cardiovascular training alone) since the brain can use up to 30 percent more kilojoules when it's ‘in gear’. So in addition to muscle-building moves, do ‘brain exercises’ that require balance and skill, such as sports, dance and aerobics classes two to three times a week for 20 minutes or more, depending on the intensity.

You can increase the number of kilojoules you burn each minute, even when you're at rest, by building more muscle. Because muscle cells are eight times more metabolically active than fat cells, muscle burns more kilojoules than fat. The greater the proportion of lean muscle mass, then, the higher your metabolic rate will be.

Consider two guys, each weighing 75kg. The first guy has 20 percent body fat, which means that 15kg is fat and the remaining 60kg is lean body mass. The second guy, however, has 10 percent body fat, which means his lean muscle mass increases to 67.5kg.

Overall, the second guy will burn more kilojoules in a day and be able to eat more to maintain his weight because his metabolic rate has increased due to the greater muscle mass.

Resistance training (like weightlifting, or working with exercise bands) is one way to build muscle and boost your metabolism. But it isn't the only way. Going one step further would be to engage in functional resistance training, or weight training that resembles everyday life, rather than linear-patterned weight training, such as biceps curls or tricep push-downs.

Functional weight training incorporates movement patterns - for example, a backward-pulling action of the arm that incorporates a twisting of the torso, coupled with a step backwards - which engage the nervous system to stimulate greater use of fuel, so you're effectively getting a double metabolic benefit.

The seven basic functional movement patterns used for everyday tasks since the days of the cavemen are pulling, pushing, lunging, squatting, bending, rotating and gait. Any resistance training exercise should use two or more of these movement patterns for maximum benefit. Aim to do resistance training - either linear or functional - three to six times a week.