We understand by now that the basis of any fat loss ‘diet’ is for us to establish a caloric deficit. This means we are eating less calories than is required for us to maintain our bodyweight and by default over time we shall lose weight.
When we establish a caloric deficit and set goals, it is obvious that in order for it to be successful we need to be adherent to it. Long term adherence done in a sustainable way will produce the best long term results for you regardless of which setup is used. Generally to do this we firstly need to disrupt energy balance intentionally to tip the scales so we are burning more that we eat on average over time.
Sounds great but what happens to our body when we do this?
Remember the energy balance equation I touched on in our Instagram post?
Here is a quick lesson. The energy we consume is one side of the equation via calories in from food and the total daily energy expenditure (TDEE) or ‘energy out’ has 4 components. TDEE = BMR + NEAT+ TEF + TEA.
Besides fat loss and positive health benefits for those who are on the higher end of body fat levels, there is an avalanche of changes to the body when we diet for an extended period of time. These changes happen over time and the extent of it will vary based on the length of time we spent dieting, size of the deficit and the amount of fat lost.
These include an increase in hunger levels, decease in satiety of foods, increase in attention to foods, reduction in leptin, increase in cortisol, reduction in thyroid hormones, reduction in sex hormones, reduction in quality of sleep, decrease in nervous system output, reduction in energy output and NEAT, decreases in motivation and ability recover from training, loss of lean mass and in extreme cases for women, amenorrhea or loss of period. These are a lot of issues and I am no expert in any of these fields but it is clear from the data that these changes happen so I will explain how it does to so you can be educated on the matter and provide some practical application as to how to minimize these effects for most.
So first off we are already eating less food since we need to intake less calories. With less food in out stomach, we will get hungrier faster and one of the changes that happens is ‘the hunger hormone’ ghrelin is increased. This raises appetite when weight loss occurs. Now one thing we can do is aim to eat foods that are much more satiating on a caloric deficit. Whole foods that are nutrient dense such as lean meats, whole grains, veggies and carbohydrate sources that are less processed. You are still free to eat other processed foods/snacks as long as you can be honest and account for it within your total caloric intake. However these foods’ has less nutrients dense, digest faster and is easier to overeat. Some people can do it but if you are on lower than usual calories, don’t suffer yourself for foods that won’t satiate you in 2 bites over a quality meal. Use the time to build good habits you can upkeep when you get off the diet. Also with an increase attention to food and our biological senses telling us that we are starving, it is advisable not to scroll Instagram food pages constantly and or play Tetris with your macros to make the best low calorie ‘snack’. Plan effectively and be mindful as these can lead you down a slope to cause severe rebounds with major eating disorders post diet. However adopting a flexible approach with a healthy mindset can make the process easier as opposed to a rigid and restrictive approach.
To add to this point, with less food intake we are already affecting the energy out aspect of the equation with a lower TEF or thermic effect of food. This equates to about 10% of the equation and will be reduced but still a consideration.
The next effect is a reduction in leptin. Leptin is one of the major controllers of all these metabolic adoptions that occur throughout. In just 3 days on a deficit we can start seeing a reduction in leptin and its effects is to control the level of stored body fat. As the level of body fat decreases, the amount of leptin secreted is reduced, and hunger is increased as mentioned above. As the body fat level increases, the leptin level increases and energy intake is reduced as that signals we are fed.
Next is cortisol which is the stress hormone and with all that adaptations happening, this can make dieting feel harder as well an increase in water retention in out body. We may not even see changes in scale weight after a while due to this. In extreme cases like contest prep for physique athletes or even referenced in The Minnesota Starvation Experiment back in 1944, Edema can occur. However this can be fixed with even a slight increase in calories to maintenance which I spoke about in the last post. Simply easing off training, reducing cardio and resting more with an increase in carbohydrates via strategic refeed days can work. Side note this strategy can also temporarily increase leptin levels but we do see it drop back down when we go back into the deficit. However what we could see in some cases after weeks of no weight loss is a sudden drop in the scale after what was mentioned above (refeeds/diet breaks). Did this mean we dropped a few pounds of fat overnight? No. Fat loss would still be happening once the deficit is kept but scale weight sometime stall. How?
So briefly, we will still be losing fat but increasingly storing water under the skin and possibly within the fat cells due to the high stress levels. After a relaxing and eating more, cortisol drops and our body starts expelling the excess water weigh and the scale will drop. It’s something Lyle McDonald coined the ‘woosh effect’ or the long term delayed fat loss effect.
I also mentioned that losing fat through dieting lowers the output of thyroid hormone (T3) and raises thyroid stimulating hormone (TSH), which also contributes to a lower metabolic rate. Now we also see other aspects of the energy out equation being directly affected. Our BMR or basal metabolic rate is lower as we drop weight simply because we weigh less and a smaller body will burn less. NEAT or Non exercise activity thermogenesis is also affected. This refers to our involuntary movements such as fidgeting or general movement. I mentioned this was the most adaptive component of the metabolism and it’s shown from studies than when calories are reduces our NEAT drops significantly. These are involuntary and it slowly changes over time. You may notice you fidget less; feel tired more, and have an urge to sit or lean up more when you get the chance. Now we can’t actively choose to fidget more or force involuntary movements consistently but one thing that can help is to have a tracker for our daily step count and aim for the same daily goal. This will somewhat help maintain fluctuation in NEAT so we can avoid our TDEE from dropping too low and stalling weight loss. Be reasonable based on your lifestyle and aim to stay active earlier in the day and not wait until 10pm at night and look to get 9000 steps in before bed because you were too lazy in the day. Things like aiming to take the stairs more, parking further away or even taking a light stroll at lunchtime will help add up.
It’s also worth speaking about training. During a caloric deficit out training will be affected by the amount we are able to do and also the amount we can recover from. So out minimum effective volume is higher in and our maximum recoverable volume is lower, which makes our window for adaption smaller. It is important to understand this so we don’t add unnecessary training volume to the current stress. I mentioned this in previous articles and will do so again, “no amount of sleep or optimal nutrition can make up for training beyond your ability to recover from doing too much training upfront.” However we should train hard because we need a sufficient stimulus to retain muscle and in some cases can still build. These situations will be if you are detrained, a beginner, obese individuals or even on ‘special anabolic supplements’. It doesn’t mean that we stop growing the first day we enter a deficit as it isn’t an on or off switch. It just doesn’t provide the same optimal anabolic environment over a sustained period over time to optimize muscle growth. However continue to push as hard as needed.
Another point to training is the consideration of cardio. When most people start dieting they’ll automatically think adding cardio is a requirement. They also start doing cardio and assume they burn the exact calories as measured on the machine or some fitness tracker. This can be skewed and cause you to assume you are burning more than you actually are. The more cardio we do we also get more efficient we get at it and it in some studies shows than with an increase in activity causes a reduction in our BMR. So it means we will compensate for the excess activity and burn less in other areas. Points can be taken from the constrained energy model whereby there is a point whereby our body will cap off the total energy burned even though we keep increasing activity. So it makes sense to not add a ton of cardio recklessly. Consider we can always create a more accurate deficit from dropping calories in via food reduction but it this way isn’t always practical. Reason being in some cased we don’t want to drop food too low where we can become deficient certain minerals, micronutrients or even become too tired to get through the day and fuel effective training. However going from very sedentary to somewhat active will be more beneficial in increasing energy expenditure as It is worth mentioning that keeping up an active lifestyle is one of the main components of keeping off the weight lost from a diet in addition eating properly for the average person and even in the obese cases.
I also mentioned the reduction in sleep quality, drop in sex hormones, loss of lean mass and loss of period for women. These happen on the more extreme end of dieting to low levels of single digit body fat levels that isn’t sustainable for daily living anyhow. In most times these are to the end of long diet phases that bodybuilding and physique athletes endure. The longer we stay in this extreme state the longer the effects are to reverse and for the average person, this isn’t a goal. If it is, rethink it, understand the effects and take a smart approach to this. Get a coach who can help. “Shameless plug- Book a consultation *wink wink*”
This isn’t a deterrent to dieting or something to turn you away from trying to lose fat. This can briefly scratch the surface of what happens over time when aim to lose weight but should be important to understand. It can put some light to why things become harder from a physiological and psychological level and show why most people quit. It’s not recommended to stay in caloric deficit for extended periods. Most people should be learning to eat at maintenance and if you are an athlete most of your off-season training should be in a caloric surplus. It doesn’t mean you have to get too far above weight classes if it applies to you. Even strength and physique athletes like bodybuilders/powerlifters have to be mindful that the majority of their early to mid training career should be out of a deficit so you can grow. The recovery period transitioning out a deficit to maintenance to eventually a surplus can also take some time for us to regularize hormones and reverse some of the down regulations that occurred to the metabolism mentioned here as well.
I spoke about how to practically calculate your estimated maintenance calories so when coming out of a deficit, utilize this method to move forward. Maintenance periods can be effectively utilized for refeeds or diet breaks also. To help temporarily ease some of the negative effects mentioned here and make the process of dieting easier.
I hope this serves as another piece to the puzzle and help you understand things a bit more. I know it was long but if you made it this far, thank you for reading. Feel free to reach out if you have any comments to add and if you like this, please share as it helps us grow to be able to provide more for you.
Feel free to book a consultation below if you would like to work with us.
-Effect of Fasting, Refeeding, and Dietary Fat Restriction on Plasma Leptin Levels https://academic.oup.com/jcem/article/82/2/561/2823443
-Metabolic adaptation to weight loss: implications for the athlete
– They Starved So That Others Be Better Fed: Remembering Ancel Keys and the Minnesota Experiment
– Moderate Weight Loss Is Sufficient to Affect Thyroid Hormone Homeostasis and Inhibit Its Peripheral Conversion
– Long-term effect of physical activity on energy balance and body composition
– Towards a Sustainable Nutrition Paradigm in Physique Sport: A Narrative Review. -Eric R. Helms, Katarina Prnjak & Jake Linardon. https://www.mdpi.com/2075-4663/7/7/172/htm
-Fat Loss Forever- How to lose Fat and keep it off. Layne Norton, Ph.D. Peter Baker.
-Advanced Nutrition and Human Metabolism (5th Edition).