Triggering Your Body to Burn Fat

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Q. I just read an article of yours on MSN. You wrote that, to lose weight, a person needs to do 60-90 minutes of cardio on most days of the week. But I was told by a trainer NOT to do this much. He said to keep it short because the first 15 min of cardio burns fat, and exercising for longer than that burns muscle, not fat. He said that it’s not good to do cardio for too long because you need to preserve, and even build, muscle since having more muscle burns calories and keeps your metabolism revved up, so I have been doing minimal cardio and lifting weights. I’ve reshaped my body but I can’t seem to lose weight or inches. Why?

A. If you’re not seeing weight or fat loss and you’re controlling what you eat, you do need to spend more than 15 minutes doing cardio. To fully explain, I’ll take you step-by-step through the several points you’ve addressed.

Burning Fat

When your body moves (or any cell in your body does any type of ”work”) it needs energy. The amount of energy needed is measured as a unit of heat—or a calorie. The fuel to produce this energy comes from several sources, mostly fat and carbs (glucose), and occasionally amino acids (protein). How and when fat is ‘”burned” (or metabolized to provide energy for the body) and how that affects body fat levels and weight is a very complex area of physiology research. There have been hundreds, maybe thousands, of studies exploring the utilization of fat for energy under a variety of different conditions. There is still much to be understood, but this is how we know it works so far:

Whether you are watching TV or running around a track, the fuel your body uses to give you the calories your cells need for energy comes from burning mostly fat and carbs. Your body nearly always burns a mix of both fat calories and carb calories. So normally, for every calorie burned, the fuels are around a 50/50 split of both fat and carbs.

How hard you are moving during exercise is one major determinant of which fuel your body will use. Carbs provide a faster energy source. So whenever you need to do something fast or produce force, carbs are the better fuel. Fats are favored during long, low-intensity activities. It’s not that you stop using one or the other fuel, it’s that the ratio of both shifts depending on your activity. In more scientific terms, you alternate between aerobic (more fat-burning) and anaerobic (more carb-burning) metabolism.

Losing Weight by Burning Calories

When it comes to weight loss, it really doesn’t matter whether you are more or less fat burning. It doesn’t matter what your calories are made of, but it does matter how many calories you burn—and the more the better. So when you are sitting—and burning more fat--you are burning only about one calorie per minute. Clearly, even though you’re in a greater fat-burning state, no one ever lost weight by sitting! (How many calories you burn depends on many factors, including how heavy you are—the more you weigh, the more you burn.)

You do burn less fat when you work anaerobically, but it doesn’t matter because you are burning more total calories. You will always burn more calories the longer or harder you exercise, no matter what your intensity is. So doing cardio for only 15 minutes makes no sense unless you are short on time. Burning BOTH fat calories and carb calories can result in fat loss or pounds off the scale.

The Ideal Amount of Cardio

How much exercise you need to do depends on your goal. Even small amounts of exercise are great for your health. Just moving a little every day can improve metabolic functions, such as how sensitive your body is to insulin and how it reacts to excess blood sugar. Exercise can also reduce your risk of heart disease and other chronic conditions. That’s why the U.S. Centers for Disease Control and Prevention and the American College of Sports Medicine recommend that all healthy adults accumulate 30 minutes of moderate intensity activity on most, if not all, days of the week. Although all types of exercise count, generally the recommendations reflect more cardio activity than lower-calorie-burning moves like strength work or stretching.

The big question is whether you’ll drop weight from this amount of exercise. The answer is that some people can. If you work a little harder in that 30 minutes, you will burn more calories and that will have a bigger effect on weight loss. If you have not been active before, then doing 30 minutes of low-intensity activity would still probably help you lose weight.

The less cardio activity you do (or the fewer calories you burn per workout), the slower the weight loss, and that’s because it’s a numbers game. In 30 minutes of moving around, you might burn 150 to 300 calories. But, theoretically, it takes burning around 3,500 calories to lose one pound of fat. So, you’re going to have to do enough workouts, at say 150 calories burned per session, to add up to 3,500 calories, or 17,500 calories for five pounds of fat, and so on.

The problem is that most people give up if they don’t get concrete results fast. Also, different people have different physiological makeups. So this theoretical caloric equation may not work perfectly in every body. That’s why more realistic fitness guidelines for losing weight or maintaining weight loss have been established. The Institute of Medicine and the USDA’s Dietary Guidelines recommend that a person do 60 to 90 minutes a day of accumulated moderate-intensity physical activity at least five days per week.

Can Exercise ‘Burn Muscle’?

This claim is slightly misleading. You certainly do not burn muscle after only 15 minutes of exercise. You start using protein (perhaps from muscle, as well as other amino-acid-containing components in the body) for energy under extreme conditions such as starvation and at the tail end of long, hard endurance events where carb stores are in short supply. The average person who works out does not need to worry about this.

Will More Muscle Rev Up Your Metabolism?

In short, probably not. The average person won’t lose muscle from doing cardio and won’t burn more fat by building more muscle, mostly because one has to eat more than usual (not diet) and lift seriously heavy weights to build more muscle. And even then that person probably won’t build enough muscle to make a difference. Dr. Joseph Donnelly and other leading exercise physiologists conducted a comprehensive review of all the research on exercise and weight loss for the American College of Sports Medicine. While resistance training was recommended for its beneficial role in potentially improving muscle strength and power, the physiologists found no evidence that increasing muscle mass enhanced weight loss, especially when combined with dieting.

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Martica is a Manhattan-based exercise physiologist and nutritionist and an award-winning fitness instructor. She has written for a variety of publications including Self , Health , Prevention , The New York Times and others. Martica is the author of seven books, including her latest, - Cross-Training for Dummies . (Read her full bio.)

Join the discussion!

1-10 of 13

Monday, February 08, 2010 10:40:33 PM

HIIT and HOC (High Octane Cardio) training are both very good for cardiovascular fitness and fat burn but the idea of doing abs before weight training is not always the best option especially if you are doing free weights as you use a lot of your core to stabilise your spine and torso. There is a method called Vertical Core Training which involves doing squats, deadlifts etc, due to the isometric contraction of the muscles it encorporates work from the transverse abdominus to create a natural ''weight belt''and rectus/obliques. Burning your core muscles out before attempting weights esecially squats, deadlifts, snatch, clean etc would not be beneficial as you are more likely to cause injury than improve fitness.

couchtatertot

Friday, February 05, 2010 10:13:13 AM

I don't exercise, just count calories and eat healthy. No alcohol, salt or sugar. I also tell myself that my body is burning fat, especially when sleeping. In 7 weeks I have gone from 173 lbs to

156 lbs today. I try and always eat breakfast usually oatmeal. Breakfast is the most important

meal. Hunger pains are good thing, it means that I am losing fat.

HeartHealth- One heart at a time

Wednesday, December 23, 2009 12:29:31 PM

This subject is huge with lots of conflicting data. Yet this is for sure, the trainer who said that you burn muscle after 15 minutes is surely wrong, and the idea that gaining muscle does not increase the metabolism is also wrong.
I think that it really depends which stage of the game you are, how active, how much you need to lose etc. To jump start the process i would recommend the Diet4idiots which explains how shifting your calories will trick the body out of storage mode, allowing you to lose weight quickly. For a more in depth plan you can read these articles from Health Experts Advice and get advice from certified trainers who are experts in the field.

60-90mins Oh my

Tuesday, December 15, 2009 8:18:07 AM

I can not believe this article! People please don't listen to this lady!!
If you are serious about getting into shape or losing weight go visit a website that specializes in that and has a ton of community members who are doing the same thing and can also help you with questions etc.
This so called msn expert is giving bad information.

takeyourpill

Sunday, August 09, 2009 1:14:16 PM

I think the workout you recommended is excellent. I truly have seen wonderful results with interval training (mixing cardio and strength training). However, as my major is in biology and I have researched the use of fuel by the human body extensively, I must inform you that our body does not use muscle protein as fuel unless it has used up all glycogen and FAT energy available to it. The human body is one of the most intelligent living forms in the universe, and it will NOT injure precious muscle tissue to use as fuel unless it's survival is threaten. Even during prolonged fasting or starvation, the body sets priorities. When the body has exausted the use of glycogen and fat stores as energy, muscle protein is the first to be catabolized. Movement is not nearly as important as maintainig wound healing and the immune response. In general the amount of fat the body contains determines the amount of time one can survive without food. The bottomline is that Tissue Proteins become the major source of glucose (energy) ONLY when glycogen and fat store are nearly exausted. I hope that was clear... I do think the author should have explained that fat stores, not only carbohydrates have to be exausted before the body uses muscle protein as energy. Oh! Our body also uses dietary protein as fuel by converting it to glucose, but this is not muscle protein.

Ula Ashore

Saturday, August 08, 2009 11:49:41 AM

I work out 5 days a week, cardio and strength-training. When I diet to lose weight I will reach a plateau eventually, then it's just a matter of keeping to the exercise plan rather than cutting more calories because the plateau will eventually subside and I'll start losing again. Honestly, it doesn't seem to matter if I do a ton of cardio, just as long as I do at least 30 min. Even if I do more I'll still hit the plateau, so I'm all in favor of taking it easy on my joints and ligaments and keeping cardio to 45 min or so on most days. Might take a bit more time to lose the extra pounds, but since you ought to be doing cardio anyway, why kill yourself sooner by trying to keep to an impossible standard that doesn't work any better than another? Give yourself a break. All you really need is consistency.

HeadCoachGreg

Monday, August 03, 2009 4:58:03 AM

Entrich and other posters are obviously advertising their own products, diets, or methods. But just as obviously , this article is controversial.

The premise that I have trouble with is that losing weight should be the goal. For health, it seems to me that losing FAT should be the goal. There is nothing wrong with or unhealthy about weighing a lot. It is very unhealthy to carry a lot of fat. Consider this: Who is more fit and likely to be more healthy: Joe, who is 6' tall, weighs 200 Lbs, with 9% body fat? Or Bill, who is 6' tall, weighs 180 Lbs, with 21% body fat? Is it the one who weighs less? or the one with less fat?

Having said (asked) that, I have to agree with Martica about the ability to build significant muscle. The chances that Joe & Bill started off the same or that Bill could EVER transform his body to be like Joe's, are extremely remote. Unless you are genetically predisposed and weight train extensively, you will NEVER look like Arnold. Also note that many very strong athletes have a lot of body fat. (check out the linemen on any pro football team.) Go figure!

Bottom line? Both aerobic and anaerobic exercise are beneficial for many health and aging reasons and both should be part of every health strategy that includes a fat loss plan.

Personally, I have made the biggest difference (very long term) by changing how I view food & nutrition and how and when I eat (NOT GRAZING!). For instance, I used to be a 'sweet-aholic'. Now, I have retrained my brain to view refined sugar as a toxin and I find the taste of sweetened things is disgusting. So even packaged/canned foods like spaghetti with sauce are just over the top sweet for me. I used to feel too fat when I was over 210. Now I feel out of control when my body fat is over 19% (about 180 lbs).

Entrich

Thursday, July 30, 2009 12:51:16 AM

Triggering your body to lose weight is a science some of the major weight loss companies has been using it calling by different names. Here something that we need to understand We need to understand that FOOD is more powerful than any prescription weight loss pills, because the FOOD that you eat can either make you THIN or FAT. You don't get fat because of a lack of exercising, that's a myth. You get fat because you don't eat the right foods at the right intervals each day.

If you begin eating 2,500 calories per day then your metabolism will adjust itself so that your body begins burning 2,500 calories per day. If you try to starve yourself by suddenly eating 1,000 calories per day then your metabolism will again ADJUST ITSELF so that your body begins to burn only 1,000 calories per day. That's why you have failed in your past dieting attempts, that's why you always seem to fail when you try and starve yourself.

Your body always "attempts" to burn the exact number of calories that you eat each day (this makes weight loss nearly impossible for many people).

The human body takes several days to "sense" any change in calories -- so if you SHIFT your calories (in a VERY special way) then your body gets "confused" and begins burning extra fat tissue (but only if you follow carefully tested eating pattern).

Here is more great Article on calorie shifting

MMarkM63

Thursday, June 25, 2009 10:28:01 AM

That is some poor advice.

When a person does stready-state cardio, i.e., running, treadmill, elliptical (non-interval), they are aerobic (using oxygen) for about the first 30 minutes. That's also when your body burns fat. Beyond that amount of time, your body goes anaerobic (without oxygen) and starts to use your muscle for fuel.

This article is old-school thinking and deals with the old cardio myth; that cardio is better for burning fat than weight training is. That couldn't be farther from the truth. Why do you think there are so many long distance runners who look so emaciated? It's because they have burned precious muscle up during these long steady-state cardio sessions.

If you want to get the biggest bang for your buck, try this:

5 minute cardio warm-up

10 minutes abs/core training

30 minutes weight training

20 minutes cardio (w/cool down)

In that exact order. That's just over an hour and you will get great results from this workout.

Here is the reasoning behind the order of my workout....

Abs/Core First:

Your abs/core aid in every movement you make. This is the most important part of your workout, IMO. People tend to put this last and then, because they get tired, they wind up not doing a very good job, or blow it off completely. It's easy to blow off, too. People HATE doing abs. Get it out of the way first.

Resistance Second:

The key to getting the maximum benefits out of strength training is to go at a slower pace, paying strict attention to your form and range of motion. If you try and do this AFTER you are all worn out from doing cardio, your form will definitely suffer. As a result, your sets/reps won't be nearly as effective and you won't see the results that you want. That's when you will get *SO FRUSTRATED!* and want to quit.

Cardio Last:

With very minor exceptions, it really doesn't take all that much technique to get on a treadmill or an elliptical machine. Cardio is about improving your breathing and your heart. Going beyond 30 minutes or so will take you OUT of the fat burning zone and IN to the muscle burning zone. You don't want that. It's counter-productive to your goal of improving your body composition. You will find that because you have already done your abs and resistance training, you won't need nearly as much cardio as you think.