Ask Dr. Halton

When is the best time to do my cardio?

I get this question all the time from new clients. The short answer is: anytime you want. I have successful clients who exercise in the mornings and I have successful clients who exercise in the evenings. I have even had a few who worked out at 10:00 PM!

Having said this, I have read research that showed early morning exercisers were more likely to stick to their routine. The reason for this is simple and makes a lot of sense. If you reserve time to work out in the early morning, very few unexpected life issues will pop up and cause you to miss the session. If you wait until the evening, any number of work or family “emergencies” can keep you from exercising.

It also depends on if you are a morning person or not. I, for one, love doing cardio in the mornings but don’t enjoy weight training in the AM. I just don’t feel as strong first thing in the morning and always save my weights for later in the day if possible.

So, in summary, do your cardio anytime that you want as long as you are doing it consistently. If you are an evening exerciser and you find you keep missing sessions because of interruptions, consider switching to the AM to improve your consistency.

Research Update

Should fruit juice be a part of your weight loss plan?

The Study

In this randomized crossover trial, 34 subjects consumed a 400 calorie preload that was either whole fruit or fruit juice. Immediately after consuming the preload, subjects were then presented with a lunch of macaroni and cheese and allowed to eat as much as they wanted. Energy intake and satiety were measured by visual analogue scale. The results were fascinating: 1) Overweight/obese subjects were significantly more hungry after the fruit juice than the solid fruit preload. 2) Subjects consumed significantly less of the macaroni and cheese lunch after ingestion of the solid fruit. 3) Total daily energy intake was significantly higher when obese participants consumed the fruit juice when compared to the solid fruit preload. International Journal of Obesity 2013; 37:1109-14

Take Home Message

Avoid fruit juice if weight loss is your goal and instead focus on whole fruit in its natural form. When you juice a fruit, you concentrate the sugar and eliminate the fiber. This process turns a food that is easy on the blood sugar to one that will cause a rapid spike in blood sugar and then a reactive hypoglycemia that will leave you feeling hungry. In this study, this effect was even more pronounced in those that were overweight or obese.

How does exercise influence hunger?

The Study

15 lean and healthy young men completed two 60 minute trials on separate occasions. Trial #1 was a treadmill run of 60 minutes at 70% of maximum aerobic capacity. Trial #2 consisted of 60 minutes of rest. After each trial, the men were shown images of high and low calorie foods while an MRI of brain activity was taken. Hunger was measured by visual analogue scale and appetite hormones were measured in the blood. The exercise session significantly decreased hunger. The exercise session significantly increased responses in reward related regions of the brain when shown images of low calorie foods and this activation was suppressed when shown images of high calorie food. Levels of ghrelin, a hormone that increases appetite, were significantly reduced after the exercise session. American Journal of Clinical Nutrition 2014; 99:258-67.

Take Home Message

For years, I have noticed anecdotally, that when a new client initiates an exercise program, their diet seems to immediately improve. I thought this was psychological, but it may just be physiological. Although more research is needed in this area, it seems that acutely after exercise, we are less interested in unhealthy food and more interested in healthy food. Consider this just one more reason to include exercise in your weight loss program.

Research Update: Sugar Consumption And Cardiovascular Disease

Added sugar intake and cardiovascular diseases mortality among US adults. JAMA Internal Medicine 2014; 174:516-24.

Objective
To investigate the association between sugar consumption and risk of cardiovascular disease.

Methods

1988-94 National Health and Nutrition Examination Survey (NHANES) data was used for this investigation. NHANES is a nationally representative sample of the U.S. population. Each participant completed a household interview and a physical examination at a mobile examination center. Diet was measured by means of a 24 hour dietary recall that was conducted through a personal interview. Sugar consumption was measured, and subjects were followed for 14 years for incidence of cardiovascular disease.

Results

In this cohort, 71.4 percent of subjects consumed more than 10% of their calories as sugar. The average sugar consumption was 15.7% of calories. When compared to subjects consuming the lowest amount of sugar (7.4% of calories), subjects consuming the most sugar (25.2% of calories) had more than double the risk of cardiovascular disease. This was after controlling for all known risk factors for cardiovascular disease, and even after controlling for overall diet quality.

Comment

Studies showing the risk of a high sugar diet are really starting to mount. There have been reported associations between sugar and risk of obesity, type 2 diabetes, hypertension, dyslipidemia, and now even stronger evidence that sugar consumption is associated with cardiovascular disease.

What makes this study interesting is that it controlled for the Healthy Eating Index score in the statistical modelling. This score measures overall diet quality. It is easy to argue in an epidemiological study such as this, that sugar is simply a marker for an unhealthy diet, so of course it will be associated with cardiovascular disease. Since this study controlled for overall diet quality, it focuses in a bit more on sugar as the culprit.

As for the mechanisms, the authors propose several possibilities:

1) Sugar has been shown in animal studies to increase hypertension.

2) Excess sugar has been shown to increase triglycerides and LDL cholesterol while lowering HDL cholesterol.

3) Sugar has been shown to increase inflammation, which is a big part of developing cardiovascular disease.

Take Home Message

If you work with me or have read any of my books you already know I am an anti-sugar guy. Sugar is everywhere and the percentages can creep up on you quickly. One soda has 35 grams of sugar, and at 140 calories, makes up 7% of total calories on a 2000 calorie diet.

Strictly limiting sugar, or better yet completely avoided it, should be a high priority for anyone who is looking to manage their weight or reduce their risk of chronic disease. The most common sources of sugar in this cohort were sugar sweetened beverages, grain based desserts (like cookies and cakes), fruit drinks, dairy based desserts (like ice cream), and candy.  Limiting these foods is an awesome place to start.  

Feature Article: Are your sleeping habits affecting your weight?

There is strong evidence that sleep plays an important role in our health. Short sleep duration has been shown to increase risk of coronary heart disease (1), type 2 diabetes (2), hypertension (3), and even early death (4). It is now clear that we can add weight gain to this list.  

Why sleep deprivation is associated with weight gain is not yet understood. There are several hypotheses that are supported by the literature. In this feature article, we’ll take a look at some of the research and make some recommendations, so that you can be sure that your sleeping habits are bringing you closer to your weight loss goals and not further away.

Sleep And Weight Gain

The association between sleep and weight gain was examined in 68,183 women in Harvard’s Nurses’ Health Study (5). After 16 years of follow up, women who slept 5 hours per night had a 32% increased chance of gaining 15 or more kg (32 pounds) when compared to women sleeping 7 hours per night. Women sleeping 7-8 hours per night had the lowest risk of major weight gain.

Sleep And Subsequent Energy Intake

Thirty men and women were studied under both short sleep duration (4 hours per night) and habitual sleep (9 hours per night) for 5 nights (6). On the 5^th day, they were given unlimited access to food and consumption was closely monitored. When subjects were sleep deprived, they consumed 295 more calories per day than when they had a full nights sleep.

Sleep And Metabolism

Fourteen normal weight males had their energy expenditure measured by indirect calorimetry on 2 separate occasions; after 8 hours of sleep and after complete sleep deprivation (7). When compared to a normal night’s sleep, energy expenditure was reduced by 5% following sleep deprivation.

Mechanisms Of Action

It is not entirely clear why sleep deprivation promotes weight gain. Several mechanisms have been supported by the research literature:

1) Sleep deprivation may alter neuronal pathways that regulate reward behaviors.

2) Sleep deprivation may increase levels of ghrelin, a hormone produced in the stomach which has been shown to increase hunger.

3) Sleep deprivation may decrease levels of leptin, a hormone which influences metabolism and satiety.

4) Fatigue resulting from sleep deprivation may reduce physical activity.

5) Sleep deprivation may decrease thermogenesis.

It is likely that several of these proposed mechanisms are working in concert.

Recommendations

I have my clients shoot for a minimum of 7 hours of sleep per night. Those that fall short do so for one of 2 reasons:

They are too busy to get a full night’s sleep. 

 

The answer to this is simply to make sleep a priority. Arrange your schedule to get to bed 7 hours before you need to wake up, no excuses. If you are watching a game or an awesome TV show, DVR it and watch the rest the next day.

They can’t fall or stay asleep.

This can be for a variety of reasons. Here are some potential solutions:

 1) Meditate for 10 minutes before you go to bed. This will get your body and mind prepared for sleep. To learn how to do this, pick up The Relaxation Response by Herbert Benson, MD.

2) White noise can be useful, particularly if you live in a city. We use an air purifier that drowns out extraneous noise 100%.

3) Make it really dark in your bedroom. Early morning light may be creeping in and waking you up. Really good blinds or a sleep mask takes care of this.

4) Don’t drink anything after 8:00 PM. Sometimes a midnight bathroom break disrupts your rhythm and then you can’t get back to sleep.

5) Limit caffeine, particularly in the late afternoon and early evening.

References

1) Ayas NT, et al. A prospective study of sleep duration and coronary heart disease in women. Archives of Internal Medicine 2003; 163 (2):205-209.

2) Ayas NT, et al. A prospective study of self-reported sleep duration and incident diabetes in women. Diabetes Care 2003; 26:380-84.

3) Tochikubo O, et al. Effects of insufficient sleep on blood pressure monitored by a new multibiomedical recorder. Hypertension 1996; 27:1318-24.

4) Wingard DL, et al. Mortality risk associated with sleeping patterns among adults. Sleep 1983; 6:102-07.

5) Patel SR, et al. Association between reduced sleep and weight gain in women. American Journal of Epidemiology 2006; 164:947-54.

6) St-Onge MP, et al. Short sleep duration increases energy intakes but does not change energy expenditure in normal weight individuals. American Journal of Clinical Nutrition 2011; 94:410-16.

7) Benedict C, et al. Acute sleep deprivation reduces energy expenditure in healthy men. American Journal of Clinical Nutrition 2011; 93:1229-36.