WeightMatters » appetite changes

Chewing Reduces Food Intake and Elevates Fullness Hormone Levels

jameslamper — Sun, 18 Sep 2011 08:16:30 +0000

Mastication is the first step in ingesting food, but the effects of mastication on energy intake and gut hormones in both obese and lean subjects have not been extensively evaluated.

Researchers in China aimed to compare the differences in chewing activities between obese and lean subjects and to examine the effects of chewing on energy intake and gut hormone concentrations in both obese and lean subjects.

Sixteen lean and 14 obese young men participated in the current research. In study 1, they investigated whether the chewing factors of obese subjects were different from those of lean subjects. In study 2, they explored the effects of chewing on energy intake. A test meal consisting of 2200 kJ (68% of energy as carbohydrate, 21% of energy as fat, and 11% of energy as protein) was then consumed on 2 different sessions (15 chews and 40 chews per bite of 10 g of food) by each subject to assess the effects of chewing on plasma gut hormone concentrations.

The results show us that compared with lean participants, obese participants had a higher ingestion rate and a lower number of chews per 1 g of food. However, obese participants had a bite size similar to that of lean subjects. Regardless of status, the subjects ingested 11.9% less after 40 chews than after 15 chews. Compared with 15 chews, 40 chews resulted in lower energy intake and ghrelin (hunger hormone) concentration and higher and cholecystokinin (fullness hormone) concentrations in both lean and obese subjects.

In conclusion, interventions aimed at improving chewing activity could become a useful tool for combating obesity.

Exercise leads to Weight Loss – The 3 Principles

WeightMatters — Fri, 11 Dec 2009 00:17:22 +0000

On Tuesday I talked about the physical compensatory responses to exercise, metabolic adaptations and changes in appetite, and yesterday I discussed the compensatory behavioural changes, such as reward and compliance. Bottom line, exercise can produce different responses in all of us.

These factors shout in favour of exercise not leading to weight loss, in fact the opposite, they suggest that exercise will produce weight gain. But this is not the whole picture. There are many people that exercise on a regular basis and do lose weight, and keep it off. So why do some people lose weight after exercise and some not?

It has to do with 3 simple principles that, when combined to create a negative energy balance, lead to weight loss – duration, intensity and frequency. When I coach my clients on their weight loss journey, it is vital that they embrace and fully understand these principles, because as their body becomes lighter as they move towards their target weight, it is increasingly harder to create a negative energy balance.

The duration of exercise is pretty simple to comprehend. How long do you exercise for? Is it a 30-minute walk around the block, or 60 minutes in the gym? Duration is all about increasing the time that you are exercising. By simply increasing exercise sessions by 5 minutes each week will compensate for a lighter body that is expending less calories.

Exercise intensity is all about how hard you are exercising. Do you choose a gentle breaststroke with your head permanently above the water, or do you choose a spin class where you are pushing yourself to the limits? As we get fitter during a weight loss programme, it is a natural progression to increase exercise intensity – it certainly means we are making a smart use of our time. Using heart rate monitors whilst running or timing yourself to reach a certain distance on the rowing machine are great measures of exercise intensity.

Frequency simply means doing exercise more frequently. Instead of walking to work once a week, it become 3 times a week Or perhaps a gym workout once week becomes 4 times a week. Exercising more often will help us make our metabolisms soar.

So despite both physiological and behavioural compensatory changes to exercise that can occur in any of us, if we master the principles of exercise duration, intensity and frequency, we can overcome the threats of weight gain by creating a negative energy balance and sustainable weight loss.

Individual variability comes screaming out at me again. Some of us find the discipline to maximise these 3 principles, while others fall at the first hurdle. The psychological skills required to conquer them is tomorrow’s story.

Think about your next workout – what will you do differently?

James

Exercise Does Lead to Weight Loss – Behavioural Change

WeightMatters — Wed, 09 Dec 2009 20:42:34 +0000

Yesterday I talked about reading an article by Dan Roberts in the Telegraph titled ‘Why your workout isn’t and the flaws in it’s argument in relation to the Physiological Adaptations which are Compensatory Responses to Exercise. I pointed out that there is individual variability in every piece of research conducted, and for this reason any expectation of Weight Loss following exercise must be valued against an individual’s physiology and psychology – one size doesn’t fit all!

You can also get Compensatory Responses to Exercise, which are Behavioural. Changes in behaviour, which arise as a result of exercise, may be automatic, resulting from physical changes such as metabolic adaptations and changes to the appetite system.

For example if metabolism slows down a person may go to sleep earlier, be more tired and less likely to move around when they are not exercising. A decrease in normal lifestyle activity resulting from fatigue or metabolic slowdown can deprive the system of a valuable source of energy expenditure.

When there are changes to the appetite system, this can lead to eating that is faster, more frequent or high in energy dense food. Other behavioural changes, which result from exercise, are volitional and purposeful.

Some people reward themselves for exercising by having a glass of wine and a pub lunch after a walk, or a coffee and a cereal bar after a swim. Misjudgement here means people eat more calories than they have expended. It may take an hour to expend only 200 calories with the most vigorous activity, while they can eat 600 calories in a slice of cake in a mater of minutes. So people who reward themselves for exercise are likely to gain weight.

A final behavioural response to activity is compliance, with the amount and intensity of activity reducing over time as a result of many complex motivational factors. We all start off with good intentions, but stuff just gets in the way.

So once again there are various behavioural reasons why research data will give mixed or sometimes inconclusive results. We are all different and will react to different life factors in different ways. Our lifestyle, physiology and psychology all collude to either help us maintain weight, gain weight or lose weight. How are your life factors balancing at the moment?

In the New Year, starting 1st January 2010, I will be starting a daily video blog of my attempt to lose weight leading to my 40th birthday on May 12th 2010. I want to share my personal experiences; feelings and insights into a diary to share with my readers, and at the same time combine it with the education that I give my clients here at the WeightMatters Clinic. Stay tuned and spread the word – it will be an interesting experiment!

James