Mr Ojomu is a 42-year-old man of African origin. He has a demanding desk-based job and frequently has to work long hours. He rarely eats regular meals, and he has developed a habit of snacking on foods with high salt, fat, and sugar contents. He routinely drinks at least 4 cups of coffee and at least one bottle of coca cola a day. Recently, he has noticed that he has put on weight and easily gets out-of-breath when walking; he feels tired when waking, often suffers muscular aches and pains, and experiences bouts of anxiety over his workload. Using three of the systems from the list below, explain what steps Mr Ojomu should take to improve his overall physical and mental health. Include in your answer how the body systems you have selected work together to normalise body functions. Human body systems The endocrine system The nervous system The digestive system The cardio-vascular system The respiratory system The urinary system

I will use the digestive system, cardiovascular system, and respiratory system for this answer. At the core of this question is an issue of health and wellness. Mr. Ojomu is not unique in his situation, and a lot of his "negative" symptoms can be addressed through relatively simple changes in diet and exercise. The question doesn't state what Ojomu's overall caloric intake is, but it is likely higher than the recommended 2,000 per day for someone of Ojomu's age. The reason that I suspect the intake is higher is because he is skipping regular meals. When this happens, people tend to over-eat while snacking. Add to that the fact that most snack foods are not generally considered very healthy.
The prompt confirms this by saying that Ojomu's snack intake is high in fat, sugar, and salt. That might be okay as long as Ojomu had a rigorous enough exercise regimen to compensate for the caloric intake; however, based on his overall tired feelings and being out-of-breath from walking, I assume that he is not getting enough exercise to maintain proper physical health.
The first thing that Mr. Ojomu needs to do is get a handle on his diet. I don't mean that he needs to adopt some kind of fad diet: those will likely lead to weight cycling and further declines in both mental and physical health. Ojomu needs to establish regular meal times. His digestive system will naturally adapt to a regular intake regimen, but, more importantly, planned meal times likely will lead to better planned meals in general.
He should focus on what types of food he is eating. The US Dietary Guidelines recommend that 45–65% of a person's diet should come from carbohydrates, 35% should be protein, and no more than 20% should come from total fat. The next thing that Ojomu is going to need to pay attention to is portion control. It won't do him any good if 6,500 of 10,000 calories are coming from carbs per day. Those percentages are based on the recommended caloric intake. Ojomu can visually figure out what his proper portion size should be by using common items to compare with. For example, the recommended portion size for meat is 3 ounces. It's a pain to measure that out, but it is equivalent in size to a deck of cards or the palm of your hand.
The next thing that Ojomu needs to focus on is exercise. He doesn't have to do anything extreme: that would be a mistake. Trying to do too much too soon is why people quite exercising. Ojomu needs to start with small, initial goals. If that starting point is walking one mile per day, then start there. The number of calories burned per mile varies with weight, but figuring 125–135 calories per mile is a good rule of thumb.
Another target goal that many people use is getting 10,000 steps per day. Walking can aid Ojomu because it's low impact. It burns calories, and it has the added benefit of increasing good cholesterol and decreasing bad cholesterol. This will have an overall positive impact on the cardiovascular system because it will help prevent the narrowing of arteries and veins which can lead to increases in blood pressure. Ojomu's respiratory health will increase too. As the heart becomes more efficient at delivering oxygen, the respiratory system doesn't have to work as hard to exchange the carbon dioxide for oxygen.
I can bring in the endocrine system at this point too. Exercise causes "feel good" hormones to be released. Exercise releases endorphins which reduce pain and quite literally make you feel good. Exercise is also proven to reduce stress, and that will help with Ojomu's work anxiety.
http://www.nationalacademies.org/hmd/Reports/2002/Dietary-Reference-Intakes-for-Energy-Carbohydrate-Fiber-Fat-Fatty-Acids-Cholesterol-Protein-and-Amino-Acids.aspx

https://www.developgoodhabits.com/benefits-of-walking/

https://www.health.harvard.edu/staying-healthy/exercising-to-relax